Group aggregates and individual reliability: The case of verbal short-term memory

Two experiments examined the generalizability of the effects of word length and phonological similarity with visual and auditory presentation in immediate verbal serial ordered recall. In Experiment 1, data were collected from 251 adult volunteers drawn from a broad cross-section of the normal population. Word length and phonological similarity in both presentation modes significantly influenced the group means. However, 43% of the subjects failed to show at least one of the effects, and the likelihood that effects appeared was highly correlated with verbal memory span. In Experiment 2, 40 subjects of the original sample were retested, 20 of whom had failed to show one or more effects in Experiment 1. Whether or not an effect had appeared for individual subjects on the first test session was a poor predictor of whether the effect would appear on retest. Finally, an analysis of subject reports demonstrated that the patterns of experimental data could be accounted for in part by the strategies that subjects reported using, and the effect of strategy was independent of the effect of span. The implications of these findings for theories of verbal short-term memory are discussed.     

Divide and conquer: how object files adapt when a persisting object splits into two

Coherent visual experience requires not only segmenting incoming visual input into a structured scene of objects, but also binding discrete views of objects into dynamic representations that persist across time and motion. However, surprisingly little work has explored the principles that guide the construction and maintenance of such persisting object representations. What causes a part of the visual field to be treated as the same object over time? In the cognitive development literature, a key principle of object persistence is cohesion: An object must always maintain a single bounded contour. Here we demonstrate for the first time that mechanisms of adult midlevel vision are affected by cohesion violations. Using the object-file framework, we tested whether object-specific preview benefits-a hallmark of persisting object representations-are obtained for dynamic objects that split into two during their motion. We found that these preview benefits do not fully persist through such cohesion violations without incurring significant performance costs. These results illustrate how cohesion is employed as a constraint that guides the maintenance of object representations in adult midlevel vision.     

Attribution of dispositional states by 12-month-olds

The ability to interpret the behavior of other individuals is essential for effective social functioning. Many investigators now believe that even young infants can recognize that agents act toward goals. Here we report three experiments suggesting that 12-month-old infants not only can recognize goal-related action, but also can interpret future actions of an actor on the basis of previously witnessed behavior in another context. The possibility that this inference is made through the attribution of mental states is discussed.     

The role of memory in the Tower of London task

The Tower of London (TOL) task is widely used as a neuropsychological test of planning. Relatively little is known of the cognitive components of the task, and in particular the role of memory in performance. The current studies on normal adults looked at the role of verbal and spatial working memory in the TOL. The effects of verbal and visuospatial dual-task manipulations on TOL performance were examined in an experiment with 36 participants. Both verbal and visuospatial executive secondary tasks caused poorer performance on the TOL; however, concurrent articulatory suppression enhanced performance. The results suggest that executive and spatial components are important in the task, and raise questions about the role of preplanning in the TOL.     

Who knows what's good to eat? Infants fail to match the food preferences of antisocial others

Humans gather most of their knowledge about the world, including objectively true facts and specific cultural norms, by observing and being taught by others. Some individuals are worthy teachers and objects of imitation, having knowledge of cultural practices and positive intentions to inform. Others are better ignored because they are ignorant, because they mean us harm, or simply because we do not wish to be “like them.” This study examines whether 16-month-olds are sensitive to the pro- or antisocial behavior of a source that demonstrates preference for two novel foods. Infants took the emotional reactions displayed by novel and previously prosocial sources, but not antisocial sources, into account when deciding what to eat. These results suggest that others’ social behavior influences infants’ likelihood to match their preferences, illustrating the influence of social evaluation on social learning.     

Thyme to touch: Infants possess strategies that protect them from dangers posed by plants

Plants have been central to human life as sources of food and raw materials for artifact construction over evolutionary time. But plants also have chemical and physical defenses (such as harmful toxins and thorns) that provide protection from herbivores. The presence of these defenses has shaped the behavioral strategies of non-human animals. Here we report evidence that human infants possess strategies that would serve to protect them from dangers posed by plants. Across two experiments, infants as young as eight months exhibit greater reluctance to manually explore plants compared to other entities. These results expand the growing literature showing that infants are sensitive to certain ancestrally recurrent dangers, and provide a basis for further exploration.     

A Qualitative Exploration of Rural African American Youth Perceptions about the Effect of Dating Violence on Sexual Health

Adolescent dating violence (ADV) remains a significant concern, particularly among rural African Americans. Few studies have explored adolescents’ perceptions about the link between ADV and sexual health and none have targeted this population. Employing qualitative methods based in Community-Based Participatory Research and theory, this study explored rural African American adolescents’ knowledge, perceptions and beliefs about the impact of ADV on sexual health. Secondary data analysis of 20 semi-structured individual interviews, conducted with older adolescents (aged 18–21), revealed participants understood the link between ADV and sexual health consequences, specifically as it related to STI and HIV prevention, condom use, and refusal of sex; and the negative impact refusing sex, communicating about HIV and other STI prevention, and negotiating condom use can have on ADV. This included: (a) negative relationship outcomes, including ADV and fear; and (b) factors that impact one’s ability to refuse sex, communicate about HIV and STI prevention, and negotiate condom use. Findings underscore the need for comprehensive ADV prevention programs for rural African Americans.