Sunday, May 9, 2021

The end of Hale magnetic cycles affect the Sun's radiative output and particulate shielding of our atmosphere through the rapid global reconfiguration of solar magnetism, which makes El Nino switch to La Nina and back

Termination of Solar Cycles and Correlated Tropospheric Variability. Robert J. Leamon  Scott W. McIntosh  Daniel R. Marsh. Earth and Space Science, February 24 2021.

Abstract: The Sun provides the energy required to sustain life on Earth and drive our planet's atmospheric circulation. However, establishing a solid physical connection between solar and tropospheric variability has posed a considerable challenge. The canon of solar variability is derived from the 400 years of observations that demonstrates the waxing and waning number of sunspots over an 11(‐ish) year period. Recent research has demonstrated the significance of the underlying 22 years magnetic polarity cycle in establishing the shorter sunspot cycle. Integral to the manifestation of the latter is the spatiotemporal overlapping and migration of oppositely polarized magnetic bands. We demonstrate the impact of “terminators”—the end of Hale magnetic cycles—on the Sun's radiative output and particulate shielding of our atmosphere through the rapid global reconfiguration of solar magnetism. Using direct observation and proxies of solar activity going back some six decades we can, with high statistical significance, demonstrate a correlation between the occurrence of terminators and the largest swings of Earth's oceanic indices: the transition from El Niño to La Niña states of the central Pacific. This empirical relationship is a potential source of increased predictive skill for the understanding of El Niño climate variations, a high‐stakes societal imperative given that El Niño impacts lives, property, and economic activity around the globe. A forecast of the Sun's global behavior places the next solar cycle termination in mid‐2020; should a major oceanic swing follow, then the challenge becomes: when does correlation become causation and how does the process work?

3 Discussion

In the previous section, we have made use of a modified Superposed Epoch Analysis (mSEA) to investigate the relationships between solar activity measures and variability in a standard measure of the variability in the Earth's largest ocean—the Pacific. We have observed that this mSEA method brackets solar activity and correspondingly systematic transitions from warm‐to‐cool Pacific conditions around abrupt changes in solar activity we have labeled termination points. These termination points mark the transition from one solar activity (sunspot) cycle to the next following the cancellation or annihilation of the previous cycle's magnetic flux at the solar equator—the end of Hale magnetic cycles.

Correlation does not imply causation; however, the recurrent nature of the ONI signal in the terminator fiducial would appear to indicate a strong physical connection between the two systems. Appendix B discusses three statistical Monte Carlo tests that show the chances of these events lining up for five cycles are remote: in summary we may reject the null hypothesis of random cooccurrences with a confidence level p < 3.4 × 10−3. We do not present an exhaustive set of solar activity proxies, but it would appear that the CRF, as the measure displaying the highest variability, as something to be explored in greater detail in coupled climate system models.

There have been many possible explanations postulated for a cosmic‐ray climate connection, including: (i) Forbush decreases inducing increased extratropical storm vorticity (Roberts & Olson, 1973; Tinsley et al., 1989) and atmospheric gravity waves propagating from the auroral ionosphere (Prikryl et al., 2009); (ii) global electric conductivity inducing changes in cloud microphysics (Harrison, 2004; Tinsley, 2000); and (iii) direct formation of ionization particles seeding cloud formation (Svensmark & Friis‐Christensen, 1997; Svensmark et al., 2017). However, the effects of cosmic rays on cloud formation are a matter of hot debate (e.g., Gray et al., 2010; Kristjánsson et al., 2002; Pierce, 2017), with even the sign of the correlation between cosmic rays and climate not agreed on. For all the debate these explanations have generated, they are all irrelevant in terms of the correlations and empirical predictions we discuss here.

Independent of the exact mechanisms of coupling solar modulation to ENSO, which are beyond the scope of this manuscript, the results discussed above and shown in Figure 5 hold for the past five solar cycles, or 60 or so years. The question must be asked, then, why has the regular pattern of Figure 5 occurred and reoccurred regularly since 1966?

As Figure 4 shows, we only have continuous cosmic‐ray observations from 1964, just before the cycle 19 terminator. The F10.7 record extends back to 1947 (near the peak of cycle 17), but Pacific Sea Surface temperatures and sunspot areas extend to the 1870s. Other than the 1915 termination of solar cycle 14, there is little evidence for such a correlation prior to the events discussed here. (Cycle 14 was notably the weakest cycle of the twentieth Century, and thus almost certainly had the highest CRF prior to the continuous observation record.) However, there certainly have been changes in the Earth's atmosphere over the twentieth Century…

3.1 Atmospheric Changes

It is probably not a coincidence that the period of terminator‐ENSO correlation corresponds to the close‐to‐monotonic rise in global sea surface temperatures over the same time period as Figure 4 (the “hockey stick” graph). Tropospheric warming leads to stratospheric cooling (Ramaswamy et al., 2006); do the effects of a colder stratosphere on the physical and chemical processes in it make it more susceptible to amplifying transient changes in solar input? Further, since about 1945, the Pacific Decadal Oscillation (Mantua et al., 1997) has been in a predominantly negative phase, the feedback to net irradiance from clouds has been increasingly negative (Zhou et al., 2016), and a ∼4%–6% decrease in cloud cover over the western Pacific (∼140–160°E) has been reported from ship‐borne observations since 1954, with a comparable increase over the mid‐Pacific (∼150–120°W; Bellomo et al., 2014). Note that 160°E is the “balance point” about which warm and cold SSTs flip in an El Niño‐La Niña transition (Pinker et al., 2017).

Thus, over the past several decades the cloud pattern in the western Pacific has adopted an almost El Niño‐like default state, consistent with an observed eastward shift in precipitation in the tropical Pacific and weakening of the Walker circulation over the last century (Deser et al., 2004; Vecchi & Soden, 2007a), and which has been tied, via simple thermodynamics, to a warmer atmosphere. Over the same past four decades timeframe, evidence for a changing Brewer‐Dobson circulation—the mass exchange between troposphere and stratosphere characterized by persistent upwelling of air in the tropics—comes from satellite and radiosonde data, which indicate a reduction in temperatures and ozone and water vapor concentrations, particularly in the tropical lower stratosphere at all longitudes (Thompson & Solomon, 2005), pointing to an accelerated tropical upwelling (Rosenlof & Reid, 2008). Domeisen et al. (2019) discuss the teleconnection of ENSO both vertically, to the stratosphere, and thence latitudinally affecting the strength and variability of the stratospheric polar vortex in the high latitudes of both hemispheres: El Niño events are associated warming and weakening of the polar vortex in the polar stratosphere of both hemispheres, while a cooling can be observed in the tropical lower stratosphere. These impacts are linked by a strengthened Brewer‐Dobson circulation, with planetary waves generated by latent heat release from tropical thunderstorms being the likely modulation mechanism (Deckert & Dameris, 2008; Domeisen et al., 2019).

Thus, it is entirely plausible that since changes in the (upper) atmosphere brought on by a strengthened Brewer‐Dobson circulation, weakened Pacific Walker circulation, and less cloudy Western Pacific, enables the relatively constant terminator‐driven changes to have sufficient “impact” to flip the system from El Niño to La Niña, independent of the actual mechanism that couples solar changes to clouds and ENSO. Such circulation changes are only likely to intensify in a future with higher tropical heat and moisture at the sea surface, affecting not only tropospheric climate but also stratospheric dynamics.

3.2 Socioeconomic Implications

Forecasting ENSO and its related climate variations is a high‐stakes societal imperative given that El Niño impacts “lives, property, and economic activity around the globe” (McPhaden, 2015). For instance, as an example of not necessarily being concerned about why or how an empirical relationship works from a forecast standpoint, Smith et al. (2016) noted “An ability to forecast the time‐averaged NAO months to years ahead would be of great societal benefit, but current operational seasonal forecasts show little skill.” Dunstone et al. (2016) thus improved the skill of 12 months ahead NAO forecasts when an 11 years (solar cycle) parameterized solar irradiance forcing term was added. Smith et al. and Dunstone et al. focused on the severity of the British winter, primarily from the viewpoint of the energy and insurance sectors.

Directly focused on catastrophic ENSO impacts, flooding in Australia during the 2010–2012 La Niñas and the ensuing economic cleanup costs (A$5–10 billion (US$4.9–9.8 billion) in Queensland alone) led to the commissioning of a Government Report on “two of the most significant events in Australia's recorded meteorological history” (Bureau of Meteorology, 2012). Similarly, the Peruvian government estimated the very strong 1997–1998 El Niño event cost about US$3.5 billion, or about 5% of their gross domestic product (GDP). Globally, United Nations estimates of El Niño‐related damage from the same event ranged from US$32 to US$96 billion. In the United States, NOAA assessed direct economic losses from that event likely exceeded US$10 billion (Weiher, 1999).

The mild winters and greater than average rainfall to the Southwest in El Niño years save US energy consumers US$2.2 billion less in fuel heating costs (Teisberg, 1999); however, the savings is lost in La Niña years with more sever winters. Agriculture is the most climate sensitive industry and climate is the primary determinant of agricultural productivity. Estimates of the impacts on U.S. agriculture of the 1997–1998 El Niño and the 1998–1999 La Niña; those losses range from US$1.5–$1.7 billion from El Niño and US$2.2–$6.5 billion from La Niña (Chen et al., 2001; Weiher & Kite‐Powell, 1999). That assessment comes with the important caveat that losses associated with El Niño‐related floods or droughts in some areas can be offset by gains elsewhere, for instance through reduced North Atlantic hurricane activity, lower winter heating bills or better harvests for certain crops—Argentinian wheat yields are strongly increased in El Niño years, for example, whereas US (and moreso Canadian) yields fall (Gutierrez, 2017). Nevertheless, combining the costs of natural disaster recovery with the costs associated with yields of major commodity crops (Gutierrez, 2017; Iizumi et al., 2014), the need to be able to predict ENSO events beyond a seasonal forecast (e.g.,‐areas/climate/wmo‐el‐ninola‐nina‐updates (World Meteorological Organization) is high.

That crop yields in North and South America, Australia, and Eurasia vary, along with regional temperature and precipitation changes, makes it clear that ENSO influences, through “teleconnections,” (e.g., Bjerknes, 1969; Domeisen et al., 2019) the global dynamics of seasonal winds, rainfall, and temperature. These teleconnections imply, indeed require, coupling throughout the atmosphere, and despite the mention of troposphere in the title of this paper, manifestations of ENSO are observed throughout the neutral atmosphere and higher.

One final economic impact consideration, also tied to global teleconnections, is the strength of Atlantic hurricane season, which is relatively strong in the first year of La Niña after an El Niño, when waters are still warm but upper‐level wind shears are favorable for cyclone genesis (Vecchi & Soden, 2007b). As such, we may expect a particularly active season in 2021, and maybe even 2020, depending on exactly when the terminator and ENSO transition occurs.

4 Conclusion

As discussed in M2014, the band‐o‐gram developed therein could be extrapolated linearly out in time. The linear extrapolation of the solar activity bands outward in time was verified in McIntosh et al. (2017) by updating the original observational analysis and comparing to the earlier band‐o‐gram. M2014 projected that sunspot cycle 25 spots would start to appear in 2019 and swell in number following the terminator in mid‐2020. Six years later, we are seeing these predictions come true with the first numbered active regions and low level (C‐class) flaring activity. Based on the mSEA of the past 60 years, an enduring warm pool in the central and western Pacific at solar minimum (ONI has been consistently positive since early 2018, even though it never got so warm to become a fully fledged strong El Niño event) was not unexpected, and we expect a rapid transition into La Niña conditions later in 2020 following the sunspot cycle 24 terminator. Given the warm waters, we project a particularly active Atlantic hurricane season in 2021, and maybe even 2020, depending on exactly when the terminator and ENSO transition occurs this year.

In conclusion, we have presented clear evidence in Figure 5 of a recurring empirical relationship between ENSO and the end of solar cycles. We have tried to avoid discussion of causation, which, due to its controversial nature could lead to dismissal of the empirical relationship, and we want open a broader scientific discussion of solar coupling to the Earth and its environment. Nevertheless, independent of the exact coupling mechanisms, the question must be asked, why has the pattern occurred and reoccurred regularly for the past five solar cycles, or 60 years? We have only a few months at most to wait to see if this Terminator‐ENSO relation continues at the onset of the coming solar cycle 25. Should this next terminator be associated with a swing to La Niña then we must seriously consider the capability of coupled global terrestrial modeling efforts to capture “step‐function” events, and assess how complex the Sun‐Earth connection is, with particular attention to the relationship between incoming cosmic rays and clouds and precipitation over our oceans. ENSO is the largest mode of atmospheric variability driving extreme weather events with large costs and so any improvement in prediction of that would be of societal benefit. 

Men are less likely than women to do listening during troubles talk

Santoro, Erik, and Hazel Markus. 2021. “How Do You Listen?: The Relationship Between How Men Listen and Women’s Power and Respect in the U.S.” PsyArXiv. May 10. doi:10.31234/

Abstract: As American culture confronts the issues raised by #MeToo, some ask, what can men do in interpersonal interactions to become allies and empower women? Building on research in linguistics, communication, sociology, as well as psychology, seven pre-registered studies investigate the relationship between how men listen during troubles talk (i.e., communication about problems) and women’s sense of power and respect. We theorize and compare two styles of effective listening: more other-focused interdependent listening (e.g., asking a question) and more self-focused independent listening (e.g., giving advice). We find that though men are less likely than women to do interdependent listening during troubles talk (Study 1), men can be encouraged to ask questions (Study 2). When investigating the effect on women of how men listen, we found that women anticipate feeling more powerful and respected when listened to by a man friend doing interdependent (vs. independent) listening (Studies 3a – 3c), particularly those women who do not endorse stereotypic gender roles (Study 3c). We partially replicated these findings in two live interaction studies involving strangers communicating over text: women felt more powerful and respected when listened to by men who asked open-ended questions compared to men who gave prescriptive, unsolicited advice (Study 5), though they did not when men simply asked more questions (Study 4). We suggest that listening can assume multiple productive forms, but that compared to independent listening, interdependent listening can serve as an everyday anti-sexist practice to attenuate rather than accentuate the gender hierarchy.

Restarting “Normal” Life after Covid-19: Systematically negative expectations regarding the future and the recovery, majoritarian fears of an economic depression, a new outbreak, & a permanent restriction on freedom

Restarting “Normal” Life after Covid-19 and the Lockdown: Evidence from Spain, the United Kingdom, and Italy. Cristiano Codagnone, Francesco Bogliacino, Camilo Gómez, Frans Folkvord, Giovanni Liva, Rafael Charris, Felipe Montealegre, Francisco Lupiañez Villanueva & Giuseppe A. Veltri. Social Indicators Research, May 8 2021.

Abstract: In this article, we examine the expectations of the economic outlook, fear of the future, and behavioural change during the first Covid-19 wave, for three European countries (Spain, the United Kingdom, and Italy) that have been severely hit. We use a novel dataset that we collected to monitor the three countries during the crisis. As outcome variables, we used expectations (e.g., economic outlook, labour market situation, recovery), fear (e.g., scenario of new outburst, economic depression, restriction to individual rights and freedom), and behavioural change across the following dimensions: savings, cultural consumption, social capital, and risky behaviour. We provide descriptive evidence that is representative of the population of interest, and we estimate the impact of exposure to shock occurred during the crisis on the same outcome variables, using matching techniques. Our main findings are the following: we detected systematically negative expectations regarding the future and the recovery, majoritarian fears of an economic depression, a new outbreak, and a permanent restriction on freedom, a reduction in saving and in social capital. Exposure to shocks decreased expected job prospects, increased withdrawal from accumulated savings, and reduced contacts with the network relevant to job advancement, whereas it had inconclusive effects over fears.

Discussion and Conclusions

In this article, we have shown the beliefs, fears, and behavioural changes of citizens in three countries (Spain, the United Kingdom and Italy), on the verge of the post Covid-19 first wave. We have discussed how the crisis always forces citizens to reassess their beliefs, their fears and their behaviour. We postulate that the climate of uncertainty and the exposure to shocks that occurred during the crisis were likely to shape those outcome variables. This contribution fills a gap in the current literature on the effects of Covid-19 and related lockdown mitigation strategy where evidence is largely missing on how the gradient of exposure to negative shocks has shaped expectations and emotions about the future, and behavioural change. We did so, by presenting a novel database from a longitudinal study conducted in three waves in Spain, the United Kingdom and Italy between April 24 and May 20 (Bogliacino et al. 2020). We focussed on the data from the third wave on expectations (general, labour market situation, recovery), fear (scenario of new outbreak, economic depression, restriction to individual rights and freedom), and behavioural change across the following dimensions: savings, cultural consumption, social capital, unhealthy lifestyle. We used, however, also the data from wave 1 and wave 2 to control for the effects of, respectively, socio-economic background and health status (from wave I), and the indirect effect via cognitive performances and preferences (from wave II).

At descriptive level, the findings support our initial hypotheses, showing that most of the respondents in the three countries report negative expectations about the future and appear entrenched by possibly unjustified fears about extremely negative scenarios. The descriptive results are consistent with the hypothesis that, given the objective and subjectively perceived radical uncertainty and the framing adopted by governments and the media, even those individuals who were not severely impacted by the pandemic and/or lockdown have updated their expectations about the future and are fearful about what awaits in the coming months. Two findings from those presented earlier suffice here to support this statement: 56% of the sample expected 2021 to be worse than 2020; an economic depression was considered somewhat likely or very likely by 91% of sample. Descriptive data are also quite unequivocal on the fact that this has produced sizeable behavioural changes for what concerns savings and social capital. Almost one third of the sample was forced to use their savings during lockdown more than in last month before the outbreak of Covid-19. This evidence suggests a tangible behavioural change and a source of worry that feeds back into the creation of negative expectations and fears. As much as 47.3% of the sample has lost contact with people relevant for their career, status or the future possibility to get a job during the lockdown as compared to before the outbreak of the pandemic. Behavioural changes are less pronounced for what concerns risky health behaviour and more polarized for the case of cultural consumption. Only 23% of the sample indicated that they adopted unhealthier lifestyle during the lockdown compared to before. On the other hand, for cultural consumption 22.1% have increased it, 36.5 maintained the same pattern, and 41.4% consumed less.

We presented a DAG positing that negative shocks have a direct effect on our outcome variables, an indirect effect via cognitive ability and preferences, and are potentially confounded by socio-economic background, and health status. Controlling for the latter three causal paths via adoption of a selection on observables research design, we have been able to conclude that the gradient of exposure to negative events (above the median) has statistically significant effects on six out of 10 outcomes. First, being severely exposed to shocks determined stronger negative expectations about one’s future jobs prospects. Second, the severity of exposure decreased the fears of an economic depression, of a new outbreak of the pandemic, and of permanent limitations to our freedom and rights, although the result was not robust to the choice of the estimator. Third, individuals who were more severely exposed to shocks used their saving more than before the pandemic outbreak in ways that are more marked than had they not experienced. Fifth, the same applied to social capital in that strong negative shocks led individuals to disregard instrumental social relations more than in presence of milder exposure to shocks.

With respect to the latter findings, it is important to remark, in particular, the first and the last results for, if consolidated, could lead to a negatively self-propelling loop. It is known that income and employment shocks exert negative effects on social capital reducing the social networks that help the unemployed to find new opportunities (Machin & Manning, 1998). Decades of research demonstrate that social connections are vital to wellbeing and coping with difficult situations (Sibley et al., 2020) and that those without social connections and with pre-existing vulnerabilities may be more at risk. As high exposure to shocks is making individuals, at the same time, more pessimistic on their jobs’ prospect and using less their social capital, there is a short-term negative interaction effect that may become a long-term effect, especially if expectations and fears are reinforced. Furthermore, the sociological literature and the literature on the psychology of class already tell us that more vulnerable groups are less used to take advantage of social capital and tend to interpret constraints and the structure of opportunities in self-limiting way. This already entrenched patterns could be multiplied by the negative shocks produced by Covid-19 and related lockdown mitigation strategies, so that the impact of the latter would become even more unequal than it is currently being shown to be. The emerging studies cited in the introduction about the inequality effect of lockdown, in fact, focus only on the tangible dimensions. Our findings suggest that there is a less tangible dimension related to habitus, beliefs, and emotions that could further exacerbate the inequalities generated by the pandemic and lockdown.

One of the strengths of the current study is that we have conducted data collection in three separate countries that have been more severely hit by the Covid-19 than other European countries. Second, the richness of the data made it possible to provide a characterization of the outcome variables that is representative of the population of interest (external validity), and to estimate a plausible counterfactual of exposure to shock to identify the causal impact (internal validity). Third, as the literature on Covid-19 is expanding rapidly, only limited studies have focused on the psychological, social, and economic consequences of the current economic halt. Nonetheless, the current study also has some limitations. First, although our surveys have been conducted for several weeks, following the panel for a longer period would have provided us with a better understanding of the long-term effects of the pandemic and the lock-down situation on people’s health and well-being, and of course ideally, one would have included a baseline pre-lockdown. Second, this study focused on three countries that have been hit hardest by the pandemic, whereby Spain and Italy had very strict lockdown regulations. If we would have included also countries that have experienced less health consequences of the Covid-19, such as Eastern European countries, or countries that implemented less strict regulations, such as the Netherlands and Germany, the comparisons between countries could have been richer. Third, regional variations are also very important to understand the first wave of the Covid-19, as it was clearly the case for Italy, but exploring them was beyond the scope of this paper.

Our findings have clear policy implications. From the first set of results, we infer the need for policies that are able to restore hope and reduce radical uncertainty. Government ought to present the citizenry with contingent mid-term plan, not only in terms of public budget resources earmarked to the purpose. Particularly, they should mitigate fears that very pessimistic scenarios will occur. The second set of implications from the results concerns the consequences of shocks. Government should recognize that the degree of exposure has been heterogenous and should design new instruments of social policy and social assistance that provide coverage even to those households which are normally outside the range of social insurance schemes, softening the deaccumulation that took place from private assets and savings. Moreover, they might introduce active labour market policies to counteract the neglect of important networking activities during the lockdowns. Finally, they should mitigate negative job prospect expectations, as this may lead to an exit of the labour force with detrimental consequences in the long term. 

Behavioral and Neural Signatures of Visual Imagery Vividness Extremes: Aphantasia vs. Hyperphantasia

Behavioral and Neural Signatures of Visual Imagery Vividness Extremes: Aphantasia vs. Hyperphantasia. Fraser Milton, Jon Fulford, Carla Dance, James Gaddum, Brittany Heuerman-Williamson, Kealan Jones, Kathryn F Knight, Matthew MacKisack, Crawford Winlove, Adam Zeman. Cerebral Cortex Communications, tgab035, May 5 2021.

Abstract: Although Galton recognized in the 1880s that some individuals lack visual imagery, this phenomenon was mostly neglected over the following century. We recently coined the terms ‘aphantasia’ and ‘hyperphantasia’ to describe visual imagery vividness extremes, unlocking a sustained surge of public interest. Aphantasia is associated with subjective impairment of face recognition and autobiographical memory. Here we report the first systematic, wide-ranging neuropsychological and brain imaging study of people with aphantasia (n = 24), hyperphantasia (n = 25) and mid-range imagery vividness (n = 20). Despite equivalent performance on standard memory tests, marked group differences were measured in autobiographical memory and imagination, participants with hyperphantasia outperforming controls who outperformed participants with aphantasia. Face recognition difficulties were reported more commonly in aphantasia. The Revised NEO Personality Inventory highlighted reduced extraversion in the aphantasia group and increased openness in the hyperphantasia group. Resting state fMRI revealed stronger connectivity between prefrontal cortices and the visual network among hyperphantasic than aphantasic participants. In an active fMRI paradigm, there was greater anterior parietal activation among hyperphantasic and control than aphantasic participants when comparing visualization of famous faces and places with perception. These behavioral and neural signatures of visual imagery vividness extremes validate and illuminate this significant but neglected dimension of individual difference.

Keywords: Aphantasia, hyperphantasia, imagery, neuroimaging, autobiographical

CEOs with large networks earn more than those with small networks; an additional connection to an executive or director outside the firm increases compensation by about $17,000 on average

From 2012... Engelberg, Joseph and Gao, Pengjie and Parsons, Christopher A., The Price of a CEO's Rolodex (May 2012). SSRN:

Abstract: CEOs with large networks earn more than those with small networks. An additional connection to an executive or director outside the firm increases compensation by about $17,000 on average, more so for “important” members such as CEOs of big firms. Pay-for-connectivity is unrelated to several measures of corporate governance, evidence in favor of an efficient contracting explanation for CEO pay.

Keywords: Executive Compensation, Social Network

JEL Classification: G30

Weight systems and the emergence of the first Pan-European money

Nicola Ialongo et al, A small change revolution. Weight systems and the emergence of the first Pan-European money, Journal of Archaeological Science (2021). DOI: 10.1016/j.jas.2021.105379


• Metal trade in Europe increases in the course of the Bronze Age.

• Systematic fragmentation of metal objects increases in the course of the Bronze Age.

• The spread of weighing technology is correlated to the spread of fragmentation.

• Cosine Quantogram Analysis and Monte Carlo simulations show that metal fragments comply with weight systems.

• Metal fragments were likely used as money.

Abstract: In the Bronze Age (c. 2300–800 BC), European communities gave up their economic independence and became entangled in a continental trade network. In this paper, we will test the hypothesis that the adoption of a ‘Pan-European’ currency has favoured the development of such a network. We define a methodology to test the money-hypothesis in pre-literate economies, based on analogies with the material characters of metallic money in the Ancient Near East. The statistical properties of metals from European hoards are compared with those of balance weights, in order to test the following expectation: if they were used as money, complete objects and fragments are expected to comply with standard weight systems. The results meet the expectation, and indicate that bronze fragments possess the same statistical properties as hack-silver money in the Ancient Near East. The sample includes approximately 3000 metal objects, collected from two test-areas: Italy and Central Europe. The sample of balance weights includes all the items known to date for pre-literate Bronze Age Europe, collected within the framework of the ERC Project ‘Weight and Value.’

Popular version: Scrap for cash: Bronze Age witnessed revolution in small change across Europe (

4. Discussion

4.1. Weight regulation

The results of the statistical analysis support the money-hypothesis for Late BA Europe, showing that metal objects were probably intentionally fragmented in order to comply with weight systems. The analogy with the Ancient Near East suggests that bronze fragments in Europe had the same function as silver fragments in Mesopotamia, i.e. they performed the basic functions of money. The joint analysis of balance weights and bronze objects suggests that monetary patterns of exchange existed in BA Europe, that they complied with a Pan-European index of value, and that they were based on the use of metals as standard media of exchange. The actual relevance of the phenomenon is difficult to quantify. For the time being, we can only observe that metal fragments were used as money frequently enough to leave measurable traces in the archaeological record; how frequently is still not possible to define. Unlike proper balance weights – that produce sharp, neatly separated clusters of mass values (Ialongo and Rahmstorf, 2019) – bronze fragments produce small clusters that stand out from a diffused background noise. FDA suggest that weight-regulated fragmentation is not very accurate. Based on the statistical analysis, we can derive that systematic fragmentation tends to produce fragments with mass values that are multiples of weight units, and that complete objects and ingots were cast with no specific mass prescription. Just like in the Mesopotamian world, the compliance with weight systems is an indirect consequence of trade, rather than a pre-defined regulation. Assessing the actual relevance of the phenomenon will require further research and a larger number of regional samples.

As to why fragments tend to assume regular mass values, we can propose a hypothesis. The typical trade situation – documented in Mesopotamian texts – includes two agents, each provided with their own weighing equipment (Peyronel, 2011). Metal fragments do not need to be weight-regulated, since each agent can easily quantify the value of the transaction. However, pre-weighed fragments would speed up the operations, by preventing the calculation of a remainder. Breaking bronze objects is relatively simple, and does not require any particular metallurgical knowledge. Experimental results show that a socketed axe made of tin bronze (8%) breaks into pieces with three blows if heated up at c. 560°, the temperature of a medium-sized campfire (Knight, 2017). The required temperature is lower if copper is alloyed with lead (Knight, 2019). In order to produce accurate fragments, one can progressively break off small bits and repeat the weighing until the desired mass is obtained. The repetitiveness of the operation increases the skill of the operator, and skill increases accuracy. Fragmentation can be performed either before or during the transaction, depending on the situation. Archaeological evidence suggests that, at least in the Late BA, bringing along small stocks of metal fragments was a rather common habit. Many burials in central and northern Europe include small boxes of organic materials, containing metal fragments and scraps, blunt tools suited for breaking metals and, sometimes, scale beams and balance weights (Pare, 1999Roscio et al., 2011). One of such boxes was recently identified among the finds of the Late BA battlefield in the Tollense Valley (Northern Germany, c. 1350–1200 BC) (Fig. 2), which attests that their use was not limited to the burial rite (Uhlig et al., 2019). These containers offer a suggestive picture of how metallic money could be carried around for everyday purposes.

For the complete objects, the absence of weight-regulation has a perfectly logical explanation. The subsample between 7 and 200 g includes every type of ornament, tool and weapon with the only exception of swords, which are exclusively represented in fragments. Since the size of a useable object is dictated by its function, there is no reason to assume that its mass should be regulated in order to fit a predetermined value.

CQA does not give significant results for ingots and ingot fragments in the shekel-range. This can depend on several factors. The fact that ingots are, on average, thicker than any other object in the sample could imply that they are more difficult to break into pieces with a predetermined mass. It could also mean that ingots and ingot fragments were not used as currency. Ingots are usually made of pure copper (e.g. Pernicka et al., 2016), and thus might have been used exclusively as raw material. It should be noted, however, that we could not compare the ingots to the balance weights in the mina-range. It is possible that, since they are on average significantly more massive than other object categories, their mass was measured in fractions of the mina rather than in multiples of the shekel. Finally, one has to consider that the main use of heavy balance weights is to weigh out bulks of goods, rather than single objects. The fact that individual ingot fragments do not comply with weight systems does not rule out the likely possibility that they were traded in weighed bulks. One way to test this could be to analyse the total weight of hoards, and verify if they conform to multiples of the European mina. Unfortunately, it is not easy to determine if a hoard is in pristine conditions, or if it underwent modifications before or after its recovery.

4.2. The value of money

Our results show that the value of bronze was quantified according to a shared frame of reference. What we define as ‘bronze,’ however, is an umbrella term for many different copper alloys, mostly containing variable proportions of tin and lead. It is theoretically possible that different alloys had different values, which could somehow hamper the circulation of metals as money. For BA Europe the puzzle is difficult to solve, as we have no direct evidence of value equivalences between different types of bronze and between bronze and other commodities.

An argument in favour of the hypothesis of the different values could be that, since bronze fragments are made of different alloys, their indiscriminate use as currency would hamper or entirely prevent their reuse as raw material. The argument, however, fails to correctly account for the evidence. Substantial quantities of fragments exist in the archaeological record and fragments were undoubtedly exchanged, regardless of whether or not one accepts their monetary use. At the same time, it would seem that metallurgists did not have problems in finding the right alloy for their purposes. This either implies that they were able to determine the alloy of fragments, or that they used fragments in limited quantities and mostly relied on other forms of raw metal, such as ingots. Hence, the argument also fails to acknowledge the relevant role of recycling (e.g. Radivojević et al., 2018). A second argument could be that some metals used in bronze alloys are rarer than others, and thus more expensive. Lead, for example, is alternatively assumed to be expensive (e.g. Johansen, 2016) or cheap (e.g. Needham and Cook, 1988), depending on whether it had to be imported (Scandinavia) or was locally available (British Isles). But if distance played such a determinant role, how can one explain, for instance, the rich metallic record of Denmark, which completely lacks copper and tin sources? The problem of value is extremely complex, and bears far-reaching implications; it basically implies theorising a continent-wide market economy for BA Europe, and cannot be addressed here. Hence, while these arguments are worthy of consideration, they should not play, for now, a decisive role in the interpretation, in one way or another.

An alternative solution could be to assume that the problem of value is not correlated to the diversity of alloys, but rather to different modes of circulation. Different models on the circulation of metals tend to focus perhaps too much on metallurgy: If fragments were mainly exchanged as money their main purpose was to circulate, not to be recycled. Moreover, their circulation was certainly not limited to metallurgists. In theory, a single fragment could circulate for decades without ever ending up in a metallurgist's hands.

Economic theory does not explain why money has value. One way to justify why worthless pieces of paper can have the same monetary function of precious metals (the so-called ‘Hahn's problem’; Hahn, 1965) is to admit that ‘if people believe that money has value, it does’ (Velde, 2021: 201). Once money is acknowledged to be valuable, however, the market dictates how much value money has. It follows that, if money can be a worthless substance, its market value is not necessarily correlated to the substance of which money is made. Since the value of money (and commodities alike) is regulated by the market, that value will be determined by the most frequent use that the market makes of the substance of which money is made. Hence, if metallurgy is the prevalent use, then it is possible that different alloys will have different values. If monetary use is prevalent, then the difference of alloys will play a minor role in the determination of value.

4.3. The origin of money? Towards a theoretical framework for money in BA Europe

Weighed currency was not the first form of money in Europe. It was, however, the first that could be potentially accepted anywhere, provided that weighing technology was available. In other words, weighing technology does not originate money, but simply provides a universally-valid frame of reference for the quantification of its value (Rahmstorf, 2016). The idea that the origin of money is correlated to technology or to the complexity of socio-economic systems implies an evolutionary paradigm, which hampers our understanding of the functions of pre-modern economies. There is nothing in economic theory that prevents the emergence of money in any given market, in economies of any complexity, and at any point in history (e.g. Jones, 1976Velde, 2021). Economic evolutionism has been shown to be based on a substantial misunderstanding of the social dynamics that regulate the modern economy (Bloch and Parry, 1989). On the contrary, it has been contended that the modern western economy is still as much embedded in social institutions as only ‘primitive’ economies were previously believed to be (e.g. Appadurai, 1986), and that the economy in ‘primitive’ societies is substantially less embedded than the evolutionary paradigm would predict (e.g. Granovetter, 1985). The contemporary approach to prehistoric money owes much to a seminal article by G. Dalton (1965), in which the author traces a sharp distinction between ‘primitive’ and ‘modern’ money. Soon after, however, J. Melitz – an economist – demonstrated that Dalton failed to acknowledge that supposedly ‘primitive’ and ‘modern’ monies have, in fact, the same functions and limitations (Melitz, 1970). Since then, the functional equivalence between ‘primitive’ and ‘modern’ money is generally accepted by most economists, economic historians, and economic anthropologists (e.g. Jones, 1976Velde, 2021Zelizer, 2000).

Money is not an evolutionary milestone, but simply a solution to the practical problem of the ‘double coincidence of wants’ (Jevons, 1875:3), stating that no one can trade with anyone who does not need or does not want whatever it is that they have to offer in payment. For example, if a pig breeder wants wheat and has only pigs to offer, they cannot obtain wheat if the crop farmer does not need or want pigs. The problem can be solved by agreeing upon using a third medium that everyone will eventually come to accept, as it is widely documented in many so-called primitive economies (e.g. Einzig, 1966Pryor, 1977). Money is not inevitable but it is convenient, as it has no requirements other than being customarily accepted by most agents in a given market. Metals represent only a limited part of all the pre-coinage monies documented either historically or ethnographically, which include perishable materials such as barley (e.g. BA Mesopotamia: Steinkeller, 2004), textiles (e.g. Classic Maya: Baron, 2018), bark-cloth (e.g. Early Colonial West Africa: Pallaver, 2015), and dried fish (e.g. Medieval Iceland: Mehler and Gardiner, 2021). Money is merely a convention, whose embodied physical media can have intrinsic value (such as silver coins) as well as none at all (i.e. banknotes) (Velde, 2021).

Concerning BA Europe, money is often believed to appear in some forms with the spread of mass metallurgy. The so-called Ösenringbarren (a type of ingot-like objects shaped as open rings common in Central Europe in the Early BA, c. 2150–1700 BC) are a common example. They show a noticeable regularity in shape, mass, and composition (Lenerz-de Wilde, 1995), and are regarded by some scholars as evidence of the earliest money in Europe (e.g. Pare, 2013Kuijpers and Popa, 2021). Since they exist several centuries before the introduction of weighing technology in Central Europe, their approximate regularity can be explained by relatively standardised moulds, and by the intuitive ability of experienced users to determine the approximate mass-equivalence of two objects simply by holding them in both hands (Kuijpers and Popa, 2021). If Ösenringbarren were indeed money – which we have no reason to doubt – their function was no different from the later, weight-regulated metal currencies. The difference is in their circulation. Since weighing technology was not available (until proven otherwise) there was no way to assess their value objectively or, for example, to calculate fractions and multiples. One can think of Ösenringbarren as a form of ‘fiduciary money’, i.e. a standard medium of exchange whose value is conventionally agreed upon, and whose intrinsic value is not relevant for the quantification of their exchange value. As it was recently proposed, fiduciary currencies can predate the emergence of commodity currencies, contrary to the common belief (Bresson, 2021). Whether classifying different types of money may or may not be the point, we would like to draw attention on the reasons why some monies are accepted in some regions and not in others. The Ösenringbarren relied on their recognisable shape, approximate size, and peculiar chemical composition in order to be accepted, because these characters were well-known and understood in the limited area where they were in common use, i.e. between southern Germany and the Czech Republic. The reason why we do not find Ösenringbarren outside this area is because those same characters were not recognised as ‘valid’ elsewhere. The spread of metallurgy undoubtedly expands trade networks, and increases the potential utility of money. The introduction of weighing technology, on the other hand, exponentially expands the user base by providing an objective frame of reference that transcends traditional cultural boundaries. At the same time, weighing technology does not alter the functions of money, and does not imply the erasure of other patterns of monetary and non-monetary exchange. Finally, if weighing technology is not a requisite for money, neither is metallurgy. By the same token, we should not prejudicially rule out a wide range of perishable commodities that are invisible in the archaeological record, but which could have been used as money before, during and after the introduction of metallurgy.

People who are involved in politics tend "to be attracted by its intellectual challenge," and tend "not to be easily shamed, nor to be particularly humble"

Bromme, Laurits, and Tobias Rothmund. 2021. “Mapping Political Trust and Involvement in the Personality Space – A Systematic Review and Analysis.” PsyArXiv. May 2. doi:10.31234/

Abstract: Individual differences in political trust and involvement in politics have been linked to Big Five personality dispositions. However, inconsistent correlational patterns have been reported. As a systematic review is still missing, the present paper provides an overview of the current state of the empirical literature. A systematic review of 43 publications (N = 215,323 participants) confirmed substantial inconsistency in the correlational patterns and corroborated a suspicion that the frequent use of low-bandwidth personality short scales might be responsible, among other reasons. In a second step, we conducted two empirical studies (N1 = 988 and N2 = 795), estimating latent correlations between the Big Five and political trust and involvement at different hierarchical levels. We found that personality relations were consistent across different subdimensions of trust (e.g., trust in politicians, institutional trust) and involvement (e.g., political interest, political self-efficacy, participation propensity) and are therefore best estimated at aggregated levels (i.e., general political trust and involvement). Meanwhile, correlational patterns differed substantially between Big Five facets, confirming that previous inconsistencies can be partly attributed to a misbalanced representation of facets in Big Five short scales and indicating that associations should be estimated at lower levels of the personality hierarchy.

Rolf Degen summarizing... Is everybody's sin nobody's sin? The prevalence of behaviors has only very small effects on their evaluation as morally good or bad

Do behavioral base rates impact associated moral judgments? Carl P. Jago. Journal of Experimental Social Psychology, Volume 95, July 2021, 104145.

Abstract: In a series of studies, we ask whether and to what extent the base rate of a behavior influences associated moral judgment. Previous research aimed at answering different but related questions are suggestive of such an effect. However, these other investigations involve injunctive norms and special reference groups which are inappropriate for an examination of the effects of base rates per se. Across five studies, we find that, when properly isolated, base rates do indeed influence moral judgment, but they do so with only very small effect sizes. In another study, we test the possibility that the very limited influence of base rates on moral judgment could be a result of a general phenomenon such as the fundamental attribution error, which is not specific to moral judgment. The results suggest that moral judgment may be uniquely resilient to the influence of base rates. In a final pair of studies, we test secondary hypotheses that injunctive norms and special reference groups would inflate any influence on moral judgments relative to base rates alone. The results supported those hypotheses.

Keywords: MoralityMoral judgmentBlameCharacterHarmNormBase rateNormalityDescriptive normInjunctive normSocial influenceCorruptConformityInfluenceMoral norm

Check also: Making moral principles suit yourself. Matthew L. Stanley, Paul Henne, Laura Niemi, Walter Sinnott-Armstrong & Felipe De Brigard. Psychonomic Bulletin & Review, May 4 2021. People’s commitment to moral principles may be maintained when they recall others’ past violations, but their commitment may wane when they recall their own violations

Up to the magical number seven (maximum number of items in short term memory): Physical limitations? Evolutionary optimal number?

Up to the magical number seven: An evolutionary perspective on the capacity of short term memory. Majid Manoochehri. Heliyon, Volume 7, Issue 5, May 2021, e06955.

Abstract: Working memory and its components are among the most determinant factors in human cognition. However, in spite of their critical importance, many aspects of their evolution remain underinvestigated. The present study is devoted to reviewing the literature of memory studies from an evolutionary, comparative perspective, focusing particularly on short term memory capacity. The findings suggest the limited capacity to be the common attribute of different species of birds and mammals. Moreover, the results imply an increasing trend of capacity from our non-human ancestors to modern humans. The present evidence shows that non-human mammals and birds, regardless of their limitations, are capable of performing memory strategies, although there seem to be some differences between their ability and that of humans in terms of flexibility and efficiency. These findings have several implications relevant to the psychology of memory and cognition, and are likely to explain differences between higher cognitive abilities of humans and non-humans. The adaptive benefits of the limited capacity and the reasons for the growing trend found in the present study are broadly discussed.

Keywords: Working memoryShort term memoryEvolution of memoryEvolution of cognitive system

7. Hypotheses concerning the capacity

Why memory span has a limited capacity or why there is an increasing trend of capacity towards humans? In the first place, I will argue the potential reasons for the limited capacity. In order to provide a more explicit discussion, the relevant studies are divided into two groups: those that based their discussion on a capacity about seven items or a temporary, passive storage (i.e., STM) and those that based their discussion on a capacity about three to four items or the focus of attention (i.e., WM).

7.1. Hypotheses of the limited capacity

7.1.1. STM hypotheses of the limited capacity

To begin with, some previous studies have suggested that “short-term memory limitations do not have a rational explanation” (Anderson, 1990, pp. 91/92) or larger capacities are biologically expensive or impossible. For instance, it has been postulated that greater STM size may have required additional tissue, which increases body mass and energetic expenditure, and therefore it is impossible with the biological characteristics of humans (e.g., Dukas, 1999). Other researchers rejected both of these assumptions (Todd et al., 2005). Moreover, the second assumption (i.e., assuming larger capacities as biologically expensive/impossible options) does not seem reasonable considering the diversity of extraordinary physiological and behavioral characteristics of different animal species. Also, if any of these suggestions is correct, we should perhaps be able to find various capacities of STM in different animals, which the present study does not indicate it.

One of the studies concerning the capacity of STM has been conducted by MacGregor (1987). Using a mathematical model, he highlighted the importance of efficient retrieval for STM. According to him, the limited capacity of STM could be the consequence of an efficiency of design. He argued that chunking facilitates retrieval when there are seven or five items in an unorganized memory. In a memory system evolved for efficiency, there is an upper effective limit to STM and a capacity beyond this limit would not be required.

In another study, Saaty and Ozdemir (2003) argued that in making preference judgments on pairs of elements in a group, the number of elements in the group should be no more than seven. The mind is sufficiently sensitive to improve large inconsistencies but not small ones and the most inconsistent judgment is easily determined. When the number of elements is seven or less, the inconsistency measurement is relatively large with respect to the number of elements involved. As the number of elements being compared is increased, the measure of inconsistency decreases slowly. Therefore, in order to serve both consistency and redundancy, it is best to keep the number of elements seven or less. When the number of elements increases past seven, the resulting increase in inconsistency is too small for the mind to single out the element that causes the greatest inconsistency to scrutinize and correct its relation to the other elements.

In a series of studies, Kareev has proposed that capacity limitation maximizes the chances for the early detection of strong and useful relations (Kareev, 19952000Kareev et al., 1997; for a controversial discussion of this hypothesis see Anderson et al., 2005Juslin and Olsson, 2005Kareev, 2005). From his standpoint, a STM capacity of size seven, which characterizes human adults, is of particular value in detecting imperfect correlations between features in the environment. The limited capacity may serve as an amplifier, strengthening signals which may otherwise be too weak to be noticed. He argued that, because correlations underlie all learning, their early detection is of great importance for the functioning and well-being of organisms. Therefore, the cognitive system might have evolved so as to increase the chances for early detection of strong correlations. In addition to the theoretical contribution, Kareev and colleagues in an experimental study found that people with smaller STMs are more likely to perceive a correlation than people with larger STMs (Kareev et al., 1997).

Some of the suggestions for the reason behind the limited capacity can be found in the studies of decision-making cognition. Here, it has been shown that people tend to rely on relatively small samples from payoff distributions (Hertwig and Pleskac, 2010). The size of these samples is often considered related to the capacity of STM (Hahn, 2014Hertwig et al., 2004Hertwig and Pleskac, 2010). In this context, a capacity-limited STM has been proposed as a possible cause (Hahn, 2014Hertwig et al., 2004Hertwig and Pleskac, 2010Todd et al., 2005) or a requirement (Plonsky et al., 2015) for relying on small samples. More relevant to the present discussion, Todd et al. (2005) suggested that the benefits of using small samples or the costs of using too much information resulted in selective pressures that have produced particular patterns of forgetting in LTM and limits of capacity in STM (see also Hahn, 2014). So, what are these costs and benefits? Limited information use can lead simple heuristics to make more robust generalizations in new environments (Todd et al., 2005). Small samples amplify the difference between the expected earnings associated with the payoff distributions, thus making the options more distinct and choice easier (Hertwig and Pleskac, 2010). Relying on small samples has also been suggested to result in saving time and energy (Plonsky et al., 2015Todd et al., 2005). Even if we assume that there is no cost (energy or time) for gathering information, by considering too much information, we are likely to add noise to our decision process, and consequently make worse decisions (Martignon and Hoffrage, 2002Todd et al., 2005). Among these, the one which is perhaps associated with strong selective forces is saving time. There are different occasions that timely decisions play a vital role in the life of animals. But perhaps of most importance is the case of hunting situations. The encounters between prey and predators were an integral part of the daily life of our ancestors through deep evolutionary time. It is also clear that the penalties for any kind of inefficiency in such encounters are immediate and fatal, which thus results in intense selection for particular cognitive abilities and predation avoidance mechanisms (see Mathis and Unger, 2012Rosier and Langkilde, 2011Whitford et al., 2019). For instance, any prey that is attacked by several predators and cannot quickly decide which one to avoid at first or which way and which method to choose for escaping or perhaps defending will be eliminated at once. A similar discussion can be developed for predators (see Lemasson et al., 2009).

Another line of studies has stressed the importance of the limited capacity for foraging activities (e.g., Bélisle and Cresswell, 1997Real, 19911992Thuijsman et al., 1995). According to it, the limited capacity may result in an overall optimization of food search behaviors. Similarly, Murray et al. (2017) have contended that the memory systems of anthropoids have been primarily evolved to reduce foraging errors. Foraging activities, however, do not appear to be the underlying reason for the capacity-limited STM. This is because, if foraging were the fundamental reason, then there would be remarkable sex differences in memory span, similar to that observed, for instance, in spatial abilities (Ecuyer-Dab and Robert, 2007Voyer, Postma, Brake and Imperato-McGinley, 2007). According to the division of labor in ancestral hunter-gatherer societies, men were predominantly hunters and women were gatherers (Ecuyer-Dab and Robert, 2007Marlowe, 2007), and it is likely that each one of these activities demands a different memory span. Namely, because a hunter has to focus on prey and ignore distracting information, while a successful gatherer can, or should, simultaneously consider many stationary targets (e.g., seeds, fruits, etc.). Contrary to this, many studies of sex differences in memory span show no significant difference (GrÉGoire and Van Der Linden, 1997Monaco et al., 2013Orsini et al., 1986Peña-Casanova et al., 2009). Foraging activities, if they were the underlying reason, could also result in remarkable differences among different species. The present study, however, does not indicate such differences. Therefore, although the limited capacity may have provided benefits for foraging activities, it seems reasonable to propose that foraging, after all, is not the main and direct reason for the limited memory space.

Among the hypotheses reviewed here, Kareev's suggestion (i.e., early detection of useful relations) is among the ones that have received relatively more attention. Also, his assumption seems reasonable in a comparative context and appears consistent with the findings of the present review. But of more importance is the fact that a memory system that has the ability of early detection of useful relations is likely to cause higher performance in associative learning and also saving time in decision making. In the case of learning, Kareev himself noted that: “Because correlations underlie all learning, their early detection and, subsequently, accurate assessment are of great importance for the functioning and well-being of organisms” (Kareev, 2000, p. 398). Leaning, certainly, is one of the first and main challenges of any cognitive system. Besides, there are broad similarities in basic forms of learning in different species (Dugatkin, 2013). It is also certain that through deep evolutionary time there has been intense selection for individuals with higher performance in learning. In this regard, Dugatkin (2013) stated that: “The ability to learn should be under strong selection pressure, such that individuals that learn appropriate cues that are useful in their particular environment should be strongly favored by natural selection” (p. 141). In summary, these considerations motivate the idea that associative learning and saving time in decision making are most likely the underlying reasons for the emergence and maintenance of limited capacity.

7.1.2. WM hypotheses of the limited capacity

There are, on the other side, some other studies of the limited capacity that based their analyses on a capacity about three to four chunks or the focus of attention (i.e., WM). Some of them will be briefly reviewed here. Sweller (2003), for instance, proposed that no more than two or three elements can be handled in WM, because any more elements would result in more potential combinations than could be tested realistically. According to him, as the number of elements in WM increases, the number of permutations rapidly becomes very large (e.g., 5! = 120). With random choice, the greater the number of alternatives from which to choose while problem solving, the less likelihood that an appropriate choice will be made.

Many other possibilities have been discussed by Cowan (Cowan, 200120052010). For instance, based on the notion that it is biologically impossible for the brain to have a larger capacity, he declared that the representation of a larger number of items could fail because together they take too long to be activated in turn (Cowan, 2010). Another discussion by Cowan is that the WM capacity limit is the necessary price of avoiding too much interference (Cowan, 2005). According to him, activation of the memory system would go out of control if WM capacity was not limited to about four items at once. A relatively small central WM may allow all concurrently active concepts to become associated with one another without causing confusion or distraction (Cowan, 2010). Oberauer and Kliegl (2006) similarly stated that:

The capacity of working memory is limited by mutual interference between the items held available simultaneously. Interference arises from interactions between features of item representations, which lead to partially degraded memory traces. The degradation of representations in turn leads to slower processing and to retrieval errors. In addition, other items in working memory compete with the target item for recall, and that competition becomes larger as more items are held in working memory and as they are more similar to each other. (p. 624).

7.2. The increasing trend of capacity

Archaeological evidence of an enhancement in the WM system has been presented by Coolidge and Wynn (2005) (see also Coolidge et al., 2013Wynn and Coolidge, 2006). The core idea of their hypothesis is a genetic mutation that affected neural networks approximately 60,000 to 130,000 years ago and increased the capacity of general WM and phonological storage. In the case of phonological storage, which is of more interest in the present review, they stipulated that: “A relatively simple mutation that increased the length of phonological storage would ultimately affect general working-memory capacity and language” (Coolidge and Wynn, 2005, p. 14). They proposed that the enhancement of WM capacities was the final piece in the evolution of human executive reasoning ability, language, and culture. From their point of view, the larger capacity is a necessary precondition for symbolic thought, which selective pressures contributed to the growth of it. They noted that an increase in WM capacities of pre-modern H. sapiens would have allowed greater articulatory rehearsal, consequently allowing for automatic long-term storage, and the beginnings of introspection, self-reflection, and consciousness. In line with Coolidge and colleagues’ hypothesis, Aboitiz et al. (2010) proposed that during the course of human evolution, a development in the phonological loop occurred. They maintained that this development produced a significant increase in STM capacity and subsequently resulted in the evolution of language.

Many researchers, at least in the field of archeology, tend to agree with the idea of enhanced WM (e.g., Aboitiz et al., 2010Haidle, 2010Lombard and Wadley, 2016Nowell, 2010Putt, 2016, for a review of criticisms, see Welshon, 2010), though there seems to be a disagreement on its time. Almost all, however, suggest a time in the Pleistocene about or after the appearance of the genus Homo (Aboitiz et al., 2010Coolidge and Wynn, 2005Haidle, 2010Putt, 2016). Some also suggest a gradual development (Haidle, 2010).

Once we accept the idea of the enhanced WM, important questions arise as to the cause and the process of this phenomenon. The enhancement of WM has been argued as a prerequisite for the evolution of some complex cognitive abilities of humans, such as language (Aboitiz et al., 2010Coolidge and Wynn, 2005) and tool use (Haidle, 2010Lombard and Wadley, 2016). For instance, Aboitiz et al. (2010) pointed out the existence of selective benefits for individuals with larger phonological capacities, which, in their view, were linguistically more apt. From their standpoint:

The development of the phonological loop produced a significant increase in short-term memory capacity for voluntary vocalizations, which facilitated learning of complex utterances that allowed the establishment of stronger social bonds and facilitated the communication of increasingly complex messages, eventually entailing external meaning and generating a syntactically ordered language. (p. 55).

In the case of tool use, Haidle (2010) argued that a basic trait of all object behaviors is the increased distance between problems and solutions. Given this, more complex object behaviors possess longer distances. According to her, during the process of tool use the immediate desire (e.g., getting the kernel of the nut) must be set aside and replaced by one or several intermediate objectives, such as finding or producing an appropriate tool. Thus, thinking must depart from the immediate problem and shift to abstract conceptualizations of potential solutions, which results in sequences of physical actions with objects appropriate to achieve a solution in the near future (see also Lombard and Wadley, 2016). Given her discussion, it is clear how individuals or populations with an enhanced WM system, which provides the possibility of maintaining and manipulating more information, could take advantage of their superiority to excel others in tool-use performance and, consequently, to win competitions.

Arguably, if we assume the enhancement of WM as a gradual process, which has started long before our common ancestor with chimpanzees (as it was found by the present study), neither tool use nor language can be considered as the primary reason for it. But complex problem solving, because of its commonness, can be nominated as the primary cause, which has then been supported by tool use and language (see also Putt, 2016). This assumption can be aided by the evidence indicating the critical role of an elaborate WM system in problem solving tasks (Logie et al., 1994Zheng et al., 2011).

After all, there are many obscure aspects regarding the evolution of WM. Needless to say, deep disagreements in the related fields and issues, such as the process and timeline of language evolution (Progovac, 2019), make the puzzle more difficult to solve. It goes beyond the limits of the present article to pursue this further, but perhaps a possible way to settle this problem is looking for advantages and disadvantages of high and low STM/WM capacities (Engle, 2010). Such findings from experimental psychology in conjunction with archaeological and comparative evidence can shed light on the evolution of the WM system.

8. Conclusion

The first and obvious implication of the present findings is that the limited capacity is the common attribute of different species of birds and mammals. The present results also indicate an increasing trend of capacity from our non-human ancestors to modern humans. Among the potential explanations of the limited capacity, associative learning and saving time in decision making, particularly because of the strong selective forces that associate with them and their vital importance for different species, seem to be more likely. On the other hand, the enhancement of the WM system appears to be a prerequisite for the evolution of some higher cognitive abilities of modern humans, such as languagetool use, and complex problem solving.

A question yet to be answered is whether the current size of STM/WM in humans is the end of the line or not. The current size has been considered by some to be the end point (e.g., MacGregor, 1987). As opposed to it, Cowan declared that it is possible to imagine that larger capacities would have been preferable or doable, but still did not happen. Therefore, our current capacity just reflects our place in the middle of an ongoing evolutionary process, not an end point. If this is the case, one might expect the present capacity to expand in the future, assuming that it offers a sufficient survival advantage (Cowan, 2005). However, the current review suggests that considering the resistance of memory span scores to the Flynn effect, it is difficult to expect substantial changes in small periods of time.

All in all, many of us, instead of the wild nature, are living in artificial and unnatural environments. Are these unnatural environments along with their overwhelming and escalating complex problem solving tasks imperceptibly pushing us towards a WM system with even a larger capacity and, if so, what is the price for that? Here, the most important point to stress is that evolution does not drive towards perfection. However, thanks to our elaborate information processing system and consciousness, we now have the ability to purposefully plan for the future of our own evolution.

The evidence reviewed in this paper shows that many species of birds and mammals are capable of performing memory strategies, although there seem to be some differences between humans and non-humans in terms of flexibility and efficiency. An enhancement in the capacity of the WM system might be the reason, or part of the reason, for the emergence of superior memory strategies in humans.

Striking similarities in the primacy and recency effect in conjunction with other evidence, such as similarities in the size of STM and performing memory strategies, suggest a similar memory structure in different species of birds and mammals. This is in accordance with Wright's inference that there is a qualitative similarity in memory processing across mammals and birds. The present findings have several implications relevant to the psychology of memory and cognition. For instance, the differences found in the ability to perform memory strategies and the size of STM, may provide an explanation for some of the differences between cognitive abilities of humans and non-humans.