‘Unwilling’ versus ‘unable’: capuchin monkeys’ (Cebus apella) understanding of human intentional action

A sensitivity to the intentions behind human action is a crucial developmental achievement in infants. Is this intention reading ability a unique and relatively recent product of human evolution and culture, or does this capacity instead have roots in our non‐human primate ancestors? Recent work by Call and colleagues (2004) lends credence to the latter hypothesis, providing evidence that chimpanzees are also sensitive to human intentions. Specifically, chimpanzees remained in a testing area longer and exhibited fewer frustration behaviors when an experimenter behaved as if he intended to give food but was unable to do so, than when the experimenter behaved as if he had no intention of giving food. The present research builds on and extends this paradigm, providing some of the first evidence of intention reading in a more distant primate relative, the capuchin monkey (Cebus apella). Like chimpanzees, capuchin monkeys distinguish between different goal‐directed acts, vacating an enclosure sooner when an experimenter acts unwilling to give food than when she acts unable to give food. Additionally, we found that this pattern is specific to animate action, and does not obtain when the same actions are performed by inanimate rods instead of human hands (for a similar logic, see Woodward, 1998 ). Taken together with the previous evidence, the present research suggests that our own intention reading is not a wholly unique aspect of the human species, but rather is shared broadly across the primate order.     

Adaptive training leads to sustained enhancement of poor working memory in children

Working memory plays a crucial role in supporting learning, with poor progress in reading and mathematics characterizing children with low memory skills. This study investigated whether these problems can be overcome by a training program designed to boost working memory. Children with low working memory skills were assessed on measures of working memory, IQ and academic attainment before and after training on either adaptive or non‐adaptive versions of the program. Adaptive training that taxed working memory to its limits was associated with substantial and sustained gains in working memory, with age‐appropriate levels achieved by the majority of children. Mathematical ability also improved significantly 6 months following adaptive training. These findings indicate that common impairments in working memory and associated learning difficulties may be overcome with this behavioral treatment.     

Abuse History, World Assumptions, and Religious Problem Solving

At a Christian university, 167 subjects completed questionnaires measuring worldview assumptions, religious problem solving, physical and emotional abuse, and subjects' beliefs about whether they had been "abused." Results indicated that worldview assumptions were not related to actual abuse histories. Instead, such assumptions were related to the subjects' beliefs that they had been abused. Subjects who believed that they had been abused had more negative views of the impersonal world, people, and themselves; they were also more likely to see events as random. Both actual abuse history and subjects' beliefs that they had been abused were related to religious problem-solving styles. Finally, problem-solving styles were related to various worldview assumptions. Results are discussed in terms of previous research on abuse and in the psychology of religion.     

The dark side of normal: A psychopathy-linked pattern called aberrant self-promotion

These studies investigate a personality and behavior pattern called aberrant self-promotion, conceptualized as a subclinical form of psychopathy. Aberrant self-promoters (ASPs) are theoretically defined as individuals characterized by a narcissistic personality configuration in combination with antisocial behavior. The first study verifies the existence of persons who manifest the ASP pattern. The second study validates the pattern, using as criteria the Revised Psychopathy Checklist (PCL-R) interview and records of antisocial behavior. In the first study a 179-item questionnaire, composed of five personality instruments, was administered to two separate samples of normal subjects (N = 214 and 367). ASPs were targeted by three methods: cluster analysis, item factor analysis, and person factor analysis. In Sample 1 the three methods demonstrated a convergence of 92 per cent in identifying the same individuals as ASPs; in Sample 2 the convergence rate was 94 per cent. In the second study 32 ASPs targeted in Study 1 were compared to 30 non-ASPS. The ASPs had significantly higher scores on the PCL-R and had committed significantly more antisocial acts than the non-ASPS. The general discussion focuses on the practical, theoretical, and measurement implications of considering aberrant self-promotion a distinct psychological motif.     

Effect of two experimental sets on sleep structure.

The effect of four perceptual sets--First Night in a sleep laboratory, Second Night in a sleep laboratory, Shock Avoidance Night, Reward Night--on the distribution of sleep was examined with 12Ss. Both the shock avoidance and the reward conditions gave results similar to those characteristically found in the First Night Effect, i.e., increases in Stage 0, Stage 1, the latency to Stage 4, the number of Awakenings, and the number of Stage Changes coupled with a decrease in Stage 1-REM. The observed effects, however, were minimal and were interpreted as giving evidence for the sturdiness of the sleep process.     

Perceptual learning in visual category acquisition

The attribute structure of a set of dot patterns was studied by having subjects segment (parse) the dots of each pattern into parts or subunits by drawing circles around groups of dots from each pattern. These parsing data were obtained for subjects who had no prior experience with the patterns and for subjects who had previously learned to identify the patterns as members of one of four categories. Analyses of the parsing data indicated that category learning increased the salience of large subunits that were similar in orientation for patterns that were members of the same category. This evidence for perceptual learning was obtained even when the category training procedure required learning to identify the patterns individually, suggesting that attribute abstraction and item learning are not incompatible. It was also obtained without an increase in overall intersubject agreement. The latter result led us to question the usefulness of intersubject agreement as an index of category knowledge.