Perception of the Ebbinghaus illusion in 5- to 8-month-old infants

The Ebbinghaus illusion is a geometric illusion based on a size-contrast between a central circle and surrounding circles. A central circle surrounded by small inducing circles is perceived as being larger than a central circle surrounded by large inducing circles. In the present study we investigated 5- to 8-month-old infants' perception of the Ebbinghaus illusion using a preferential-looking paradigm. We measured the preference between a central circle surrounded by small inducing circles (overestimated figure) and a central circle surrounded by large inducing circles (underestimated figure). Infants showed a significant preference for the overestimated figure when the central circle was flashing, but not when it was static. Furthermore, there was no preference between the two figures when the central circles were removed. These results suggest that infants' preference reflects their perception of the size illusion of the central circle. There is a possibility that 5- to 8-month-old infants perceive the Ebbinghaus illusion.     

Marmosets as a next-generation model of comparative cognition

Common marmosets have traditionally been used in fields such as comparative psychology, cognitive neuroscience, and ethology, and as animal models of human disease research because of their relatively small body size, high reproductive rate, similar breeding system characteristics to those of humans, high dependency on vocal communication, and behavioral effects from drug administration that resemble those of humans. Although the animal has proved to be quite advantageous in animal model research in comparison to rodents, and has specific ecological and evolutionary characteristics that are worthy of exploration, few attempts have been made until recently to combine both types of approach. Thus, supported by neuroscientific methodologies that have recently been developed using this species, the authors suggest that the evolutionary origins of cognitive and social functions common to or differentiated in primates, could be uncovered through research that explores the behavioral and neural bases of cognition in the marmosets.     

Collective action and subordinate group identity in a simulated society game

Abstract: This research examined the effects of upward mobility and resource disparity on subordinates’ collective action and group identity in a context of intergroup negotiation by using a simulated society (SIMSOC) game. According to the social identity theory, it was hypothesized that when individual mobility opportunities for a subordinate group increase, the members of the subordinate group are less likely to participate in collective actions and to appreciate the merits of their own group identity. Four hundred and fifty‐four undergraduates participated in 12 separate SIMSOC games. For each game, approximately 40 undergraduates were divided into dominant and subordinate groups. Each of the four combinations of high/low levels of upward mobility and large/small resource disparity was played out three times. Subordinates in the low‐mobility condition acted collectively more frequently and evaluated their own group more positively than those in the high‐mobility condition. A signifificant positive correlation between the frequency of subordinates’ collective action and in‐group favoritism was found.