Sunday, October 15, 2017

Rhesus macaques expect others to dynamically update their representations of unseen objects

What do monkeys know about others’ knowledge? Lindsey A. Drayton, Laurie R. Santos. Cognition, Volume 170, January 2018, Pages 201–208.

•    Monkeys expect others to track a hidden object during a rotational displacement task.
•    Monkeys do not show a curse of knowledge bias.
•    Results are consistent with the hypothesis that monkeys represent what others know.

Abstract: Recently, comparative psychologists have suggested that primates represent others’ knowledge states. Evidence for this claim comes from studies demonstrating that primates expect others to maintain representations of objects when those objects are not currently visible. However, little work has explored whether nonhuman primates expect others to share the more sophisticated kinds of object knowledge that they themselves possess. We therefore investigated whether primates attribute to others knowledge that is acquired through the mental transformation of a static object representation. Specifically, we tested whether rhesus macaques (Macaca mulatta) expected a human demonstrator to solve a difficult rotational displacement task. In Experiment 1, monkeys watched a demonstrator hide a piece of fruit in one of two boxes. The monkey and the demonstrator then watched the boxes rotate 180°. We found that monkeys looked longer when the demonstrator reached into the box that did not contain the fruit, indicating that they expected her to be able to track the fruit to its current location. In Experiment 2, we ruled out the possibility that monkeys simply expected the demonstrator to search for the food in its true location. When the demonstrator did not witness the rotation event, monkeys looked equally long at the two reaching outcomes. These results are consistent with the interpretation that rhesus macaques expect others to dynamically update their representations of unseen objects.

Keywords: Theory of mind; Knowledge representation; Comparative cognition; Object knowledge

Leaving late: Understanding the extent and predictors of college late departure

Leaving late: Understanding the extent and predictors of college late departure. Zachary Mabel, Tolani A. Britton. Social Science Research,

Abstract: Research on college dropout has largely addressed early exit from school, even though a large share of students who do not earn degrees leave after their second year. In this paper, we offer new evidence on the scope of college late departure. Using administrative data from Florida and Ohio, we conduct an event history analysis of the dropout process as a function of credit attainment. Our results indicate that late departure is widespread, particularly at two- and open-admission four-year institutions. We estimate that 14 percent of all entrants to college and one-third of all dropouts completed at least three-quarters of the credits that are typically required to graduate before leaving without a degree. Our results also indicate that the probability of departure spikes as students near the finish line. Amidst considerable policy attention towards improving student outcomes in college, our findings point to promising new avenues for intervention to increase postsecondary attainment.

Keywords: Postsecondary completion; College dropout; Late departure; Human capital

How Disgust Becomes Law

Patrick, Carlton and Lieberman, Debra, How Disgust Becomes Law (August 24, 2017). Forthcoming in The Moral Psychology of Disgust, Nina Strohminger & Victor Kumar (Eds.), London: Rowman & Littlefield, 2018.

Abstract: This chapter provides a psychological examination of the many ways in which disgust permeates the law. Using an evolutionary lens, the chapter explores the various adaptive functions of disgust, and shows how those functions can be co-opted by psychological systems designed to generate and enforce moral norms. In doing so, the chapter also provides an explanation for why and how many of the behaviors we view as "disgusting" tend to become behaviors we label "wrong."

Keywords: evolutionary analysis in law, legal theory, disgust and the law, law and psychology, behavioral biology, morality, evolutionary psychology

A second way that disgust is used by systems sensitive to alliance formation and group condemnation relates to communication. When individuals broadcast signals of disgust, they provide a means to infer the likelihood of alliance formation in the service of condemning a particular behavior. Personal disgust, when echoed by another person and then another person and then another, is a cue of mental alliance that can facilitate the formation of a coalition targeting particular individuals engaging in the disgust eliciting act. Disgust is not unique in this respect. Hearing the terms “I hate people who tailgate on the highway” can rally the troops as well. President Trump (and he is hardly the first) has continually attempted to incite fear and anger in an attempt to marginalize Mexicans seeking to immigrate to the US. These kinds of phrases give an indication of others’ willingness to form an alliance condemning others. In this way, disgust language and facial expressions can either be or not be actual felt disgust. One can personally feel disgust and communicate this, or one can merely use the language of disgust.

Disgust originates largely to reduce contact with foreigners, and the deviant or marginalized

Rottman, J., DeJesus, J. M., & Gerdin, E. (forthcoming). The social origins of disgust. In N. Strohminger & V. Kumar (Eds.), The moral psychology of disgust. London: Rowman & Littlefield.

Despite being perfectly nutritious, consuming bugs is considered gross in many cultures [...] What is the function of such an irrational response, one that may continue to endanger the natural environment? Do people experience disgust toward insects because of perceived disease risks? Are people reacting to the reminder that they are eating an animal, in the same way that many people react negatively to eating a whole fish (with its head and eyes) compared to a fish fillet? We argue that social risks may instead be motivating this reaction. More broadly, moving beyond the example of entomophagy, we claim that disgust is much more deeply enmeshed in social and moral considerations than has been previously acknowledged. [...] In this chapter, we propose an alternative to the recurrent claim that disgust evolved for the sole purpose of facilitating the avoidance of toxins and infectious disease [...]

We do not deny that disease avoidance is a crucial element of disgust, but we believe that there is more to the story. We argue that a central component of the adaptive value of disgust lies in the motivation it provides for reducing contact with people who are considered to be deviant or marginalized, both for disease-related and reputation-related reasons (see Chudek and Henrich 2011, for a discussion of the adaptive function of social norms). We hereby introduce the “Social Origins” hypothesis as a crucial addition to the Physical Origins hypothesis to provide a more complete evolutionary account of disgust. According to our hypothesis, disgust originated largely as a functional response for preventing contact with foreigners or people acting in non-normative ways. This response serves a dual adaptive purpose: reducing human-borne illnesses and maintaining reputational status within one’s social group, either separately or simultaneously. Therefore, while avoiding pathogens is a crucial component of a full explanation of disgust’s origins and functions, we argue that simple disease avoidance was not the sole or even the primary driver of the evolution of disgust in humans.

Manipulating courtship opportunities made Drosophila pseudo. sing longer, faster, and fly and move faster

Mate choice intensifies motor signalling in Drosophila. Allan Debelle et al. Animal Behaviour, Volume 133, November 2017, Pages 169–187.

•    We experimentally increased or decreased sexual selection in Drosophila populations.
•    We perform an in-depth analysis of the response of a motor signal (pulse rate).
•    Polyandrous males sing at a faster rate and do so for longer than monogamous males.
•    Fast song rates are associated with overall increased male motor performance.
•    Increasing the opportunity for mate choice increased male motor performance.

Mate choice has the potential to act on the evolution of motor performance via its direct influence on motor sexual signals. However, studies demonstrating this are rare. Here, we performed an in-depth analysis of Drosophila pseudoobscura courtship song rate, a motor signal under mate choice in this species, and analysed the response of this signal to sexual selection manipulation using experimental evolution. We show that manipulating the opportunity for sexual selection led to changes in song production rate and singing endurance, with males from the polyandrous populations producing faster song rates over longer time periods than males from monogamous populations. We also show that song rate was correlated with estimates of overall courtship vigour. Our results suggest that the action of mate choice on a motor signal has affected male motor performance displayed during courtship. We consider potential selective benefits associated with changes in motor performance, including condition-dependent signalling, and discuss the implications of these results for the study of motor signals under sexual selection.

Keywords: courtship song; Drosophila pseudoobscura; experimental evolution; interpulse interval; mate choice; motor performance; sexual selection

My commentary: Manipulating courtship opportunities made Drosophila pseudo. sing longer, faster, and fly and move faster. We are not so distant...