Gaze following and gaze priming in lemurs

Although primates have often been found to co-orient visually with other individuals, members of these same species have usually failed to use co-orientation to find hidden food in object-choice experiments. This presents an evolutionary puzzle: what is the function of co-orientation if it is not used for a function as basic as locating resources? Co-orientation responses have not been systematically investigated in object-choice experiments, and requiring co-orientation with humans (as is typical in object-choice tasks) may underestimate other species’ abilities. Using an object-choice task with conspecific models depicted in photographs, we provide experimental evidence that two lemur species (Eulemur fulvus, n = 4, and Eulemur macaco, n = 2) co-orient with conspecifics. Secondly, by analysing together two measures that have traditionally been examined separately, we show that lemurs’ gaze following behaviour and ultimate choice are closely linked. Individuals were more likely to choose correctly after having looked in the same direction as the model, and thus chose objects correctly more often than chance. We propose a candidate system for the evolutionary origins of more complex gaze following: ‘gaze priming.’     

Body posture and gender impact neural processing of power-related words

Judging others’ power facilitates successful social interaction. Both gender and body posture have been shown to influence judgments of another’s power. However, little is known about how these two cues interact when they conflict or how they influence early processing. The present study investigated this question during very early processing of power-related words using event-related potentials (ERPs). Participants viewed images of women and men in dominant and submissive postures that were quickly followed by dominant or submissive words. Gender and posture both modulated neural responses in the N2 latency range to dominant words, but for submissive words they had little impact. Thus, in the context of dual-processing theories of person perception, information extracted from both behavior (i.e., posture) and from category membership (i.e., gender) are recruited side-by-side to impact word processing.     

Who Counts as Human? Antecedents to Androcentric Behavior

People view men as typically human, although some conditions may make this more or less likely. Language has been implicated as one factor, with masculine generic language (e.g., he used neutrally) leading to more androcentrism relative to its alternatives. However, the influence of two types of alternatives (e.g., they vs. he or she) remains unclear. The present study asked 297 male and female online participants from the United States to select typical representations of humanity from a set of White and Black male and female faces. The wording for the concept humanity was manipulated to be either a typical member of mankind, a typical human, or a typical man or woman (or woman or man). Overall, participants selected more White targets. Participants also selected more male targets, but the degree to which that was the case was affected by wording and participant’s gender. Participants, particularly male participants, in the mankind and human wording conditions were more likely to select a male target as representative, whereas in the man or woman condition, participants’ choices did not differ from chance. Thus, androcentric thinking may be more mutable than previously surmised, varying by participants’ gender and by context.     

Meeting the educational needs of special populations

We evaluated the Advanced Placement (AP) program from the point of view of intellectually precocious youth and their subsequent educational-vocational outcomes, analyzing normative and idiographic longitudinal data collected across 30 years from 3,937 participants. Most took AP courses in high school, and those who did frequently nominated an AP course as their favorite. Students who took AP courses, compared with their intellectual peers who did not, appeared more satisfied with the intellectual caliber of their high school experience and, ultimately, achieved more. Overall, this special population placed a premium on intellectual challenge in high school and found the lack of such challenge distressing. These findings can inform contemporary educational policy debates regarding the AP program; they also have general implications for designing and evaluating educational interventions for students with special needs.     

Alcohol self-administration by rats in the presence of a tangible object

The authors used the sucrose-substitution procedure to train operant self-administration of a 10% alcohol solution in 8 Long-Evans rats. After they established stable responding, they began a 10-session baseline. A 10-session experimental phase followed the baseline phase. During the experimental phase, the authors placed a large glass marble in the center of the experimental chambers before self-administration sessions. The presence of the marble decreased the rats' responding and alcohol intake significantly. The authors discussed the results in terms of distraction and the effects of concurrently available reinforcers on alcohol self-administration.     

Continuity and change in the life story: a longitudinal study of autobiographical memories in emerging adulthood

If a person's internalized and evolving life story (narrative identity) is to be considered an integral feature of personality itself, then aspects of that story should manifest some continuity over time while also providing evidence regarding important personality change. Accordingly, college freshmen and seniors provided detailed written accounts of 10 key scenes in their life stories, and they repeated the same procedure 3 months and then 3 years later. The accounts were content analyzed for reliable narrative indices employed in previous studies of life stories: emotional tone, motivational themes (agency, communion, personal growth), and narrative complexity. The results showed substantial continuity over time for narrative complexity and positive (vs. negative) emotional tone and moderate but still significant continuity for themes of agency and growth. In addition, emerging adults (1) constructed more emotionally positive stories and showed (2) greater levels of emotional nuance and self-differentiation and (3) greater understanding of their own personal development in the 4th year of the study compared to the 1st year. The study is the first to demonstrate both temporal continuity and developmental change in narrative identity over time in a broad sampling of personally meaningful life-story scenes.     

Relative reinforcing effects of different oral ethanol doses in rhesus monkeys

The relative reinforcing effects of different doses of orally delivered ethanol were evaluated. Mouth-contact responding by rhesus monkeys was measured under concurrent fixed-ratio fixed-ratio schedules of liquid delivery (0.67 ml/delivery) from each of two spouts during daily 3-hr sessions. Experiment 1 examined persistence of responding with ethanol (2%, 8%, and 32% wt/vol) and water available. When fixed-ratio values from 8 to 128 were tested, the number of ethanol deliveries obtained per session decreased as the response requirement increased. The decrease in deliveries was less at higher than at lower ethanol concentrations, however. Experiment 2 examined choice between two ethanol concentrations under concurrent fixed-ratio 16 schedules (4% vs. 8%, 4% vs. 16%, 8% vs. 16%, 2% vs. 8%, 2% vs. 32%, 8% vs. 32%). Higher concentrations (16%, 32%) generally maintained more responding than concurrently available concentrations of 8% or less. An exception was the observation of a preference for 8% over 32% ethanol. When the fixed-ratio value was increased, however, the relative preference for these two doses was reversed so that 32% ethanol maintained more responding than 8% ethanol. Thus, the direction of the preference depended on the size of the response requirement. These results indicate that the reinforcing effects of ethanol increase with dose.