The consequences of race for police officers' responses to criminal suspects

The current work examined police officers' decisions to shoot Black and White criminal suspects in a computer simulation. Responses to the simulation revealed that upon initial exposure to the program, the officers were more likely to mistakenly shoot unarmed Black compared with unarmed White suspects. However, after extensive training with the program, in which the race of the suspect was unrelated to the presence of a weapon, the officers were able to eliminate this bias. These findings are discussed in terms of their implications for the elimination of racial biases and the training of police officers.     

Category learning and multiple memory systems

Categorization is a vitally important skill that people use every day. Early theories of category learning assumed a single learning system, but recent evidence suggests that human category learning may depend on many of the major memory systems that have been hypothesized by memory researchers. As different memory systems flourish under different conditions, an understanding of how categorization uses available memory systems will improve our understanding of a basic human skill, lead to better insights into the cognitive changes that result from a variety of neurological disorders, and suggest improvements in training procedures for complex categorization tasks.     

Mental and physical practice schedules in acquisition and retention of novel timing skills

Research has indicated that random physical practice of a motor skill enhances effects of long-term learning more than blocked practice. Moreover, the use of mental rehearsal coupled with physical practice has been shown to accelerate motor skill acquisition in many different contexts and is better than no practice at all. Others have found that some mental rehearsal strategies are better than others for maximizing performance. This study examined how combinations of mental and physical practice schedules affected the learning of a coincidence timing task. 30 college students were randomly assigned to one of four treatment groups involving combinations of imagery and physical practice. Three tasks were utilized, each involving a particular speed (slow, medium, fast) on the Bassin Anticipation Timer. Conclusions were based on a three-way analysis of variance, using type of mental practice, type of physical practice, and sex as between-group factors, conducted separately for acquisition and retention trials. Type of physical practice was significantly related to performance. On the acquisition trials, random practice was associated with larger mean errors than blocked practice; however, the reverse was true for retention trials. There was no significant effect of type of mental practice in either the acquisition or retention phase. Sex was significantly related to performance for the retention trials only, where the 15 men made smaller errors than the 15 women.     

Learning about life and death in early childhood

have argued that young children initially understand biological phenomena in terms of vitalism, a mode of construal in which "life" or "life-force" is the central causal-explanatory concept. This study investigated the development of vitalistic reasoning in young children's concepts of life, the human body and death. Sixty preschool children between the ages of 3 years, 7 months and 5 years, 11 months participated. All children were initially given structured interviews to assess their knowledge of (1) human body function and (2) death. From this sample 40 children in the Training group were taught about the human body and how it functions to maintain life. The Control group (n=20) received no training. All 60 children were subsequently reassessed on their knowledge of human body function and death. Results from the initial interviews indicated that young children who spontaneously appealed to vitalistic concepts in reasoning about human body functioning were also more sophisticated in their understanding of death. Results from the posttraining interviews showed that children readily learned to adopt a vitalistic approach to human body functioning, and that this learning coincided with significant development in their understanding of human body function, and of death. The overall pattern of results supports the claim that the acquisition of a vitalistic causal-explanatory framework serves to structure children's concepts and facilitates learning in the domain of biology.     

Emergence of joint attention: relationships between gaze following,social referencing,imitation, and naming in infancy

The authors investigated the extent to which the joint-attention behaviors of gaze following, social referencing, and object-directed imitation were related to each other and to infants' vocabulary development in a sample of 60 infants between the ages of 8 and 14 months. Joint-attention skills and vocabulary development were assessed in a laboratory setting. Split-half reliability analyses on the joint-attention measures indicated that the tasks reliably assessed infants' capabilities. In the main analysis, no significant correlations were found among the joint-attention behaviors except for a significant relationship between gaze following and the number of names in infants' productive vocabularies. The overall pattern of results did not replicate results of previous studies (e.g., M. Carpenter, K. Nagell, & M. Tomasello, 1998) that found relationships between various emerging joint-attention behaviors.     

Fostering group identification and creativity in diverse groups: the role of individuation and self-verification

A longitudinal study examined the interplay of identity negotiation processes and diversity in small groups of master's of business administration (MBA) students. When perceivers formed relatively positive impressions of other group members, higher diversity predicted more individuation of targets. When perceivers formed relatively neutral impressions of other group members, however, higher diversity predicted less individuation of targets. Individuation at the outset of the semester predicted self-verification effects several weeks later, and self-verification, in turn, predicted group identification and creative task performance. The authors conclude that contrary to self-categorization theory, fostering individuation and self-verification in diverse groups may maximize group identification and productivity.     

A neurobiological theory of automaticity in perceptual categorization

A biologically detailed computational model is described of how categorization judgments become automatic in tasks that depend on procedural learning. The model assumes 2 neural pathways from sensory association cortex to the premotor area that mediates response selection. A longer and slower path projects to the premotor area via the striatum, globus pallidus, and thalamus. A faster, purely cortical path projects directly to the premotor area. The model assumes that the subcortical path has greater neural plasticity because of a dopamine-mediated learning signal from the substantia nigra. In contrast, the cortical-cortical path learns more slowly via (dopamine independent) Hebbian learning. Because of its greater plasticity, early performance is dominated by the subcortical path, but the development of automaticity is characterized by a transfer of control to the faster cortical-cortical projection. The model, called SPEED (Subcortical Pathways Enable Expertise Development), includes differential equations that describe activation in the relevant brain areas and difference equations that describe the 2- and 3-factor learning. A variety of simulations are described, showing that the model accounts for some classic single-cell recording and behavioral results.     

Participant loss due to "fussiness" in infant visual paradigms: a review of the last 20 years

One hundred and one published articles that used visual habituation or violation-of-expectation techniques with infants of 12 months or younger were surveyed. Information was compiled on the number of infants who failed to complete experimental procedures due to "fussiness" or other factors. Also noted for each experiment was whether or not infants as a group demonstrated differential responding to the test display. On average 13.7% (range 0-62%) of infants failed to complete these visual procedures as a result of fussiness. There was no correlation between experimental outcome and infant attrition due to fussiness or to any other factor. We thus found no evidence to suggest that differential exclusion rates systematically influence experimental outcomes. However, we urge researchers to provide operational definitions of "fussiness."