Application of social identity theory in group therapy with stigmatized adults.

Social identity theory was applied in group therapy for adults with mild mental retardation. Social identity theory suggests that social group membership, also called collective identity, has an impact on self-esteem. Individuals will try to maintain self-esteem by viewing their social groups positively. This may not be possible for individuals who are members of a stigmatized group. However, it may be possible to enhance self-esteem by broadening one's awareness of collective identity. Furthermore, being able to positively view other individuals who are co-members of one's own stigmatized group can also have positive consequences for self-esteem. A clinical vignette demonstrates this process in group therapy. Results are discussed as being applicable to members of various stigmatized groups.     

Effects of power on perceived and objective group variability: evidence that more powerful groups are more variable

The perception of group variability is affected by social power and status. Three different mechanisms may be responsible for these effects: (a) the power of the perceiver affects perceived group variability; (b) the power of the perceived group affects its perceived variability; and (c) the power of the group affects its actual variability. Two studies are reported to tease apart these three mechanisms and provide support for the third. In the first study, high- and low-power groups interacted and subsequently judged each other. In the second study, participants observed and rated the Study 1 groups, either knowing their power relationship or not. Results suggest that members of high-power groups manifest greater interpersonal variability than members of low-power groups.     

Discrimination of individual vocalizations by black-capped chickadees (Poecile atricapilla)

The auditory perceptual abilities of male black-capped chickadees (Poecile atricapilla) were examined using an operant go/no-go discrimination among 16 individual vocalizations recorded at 5 m. The birds learned to discriminate about equally well among eight male chickadee fee-bee songs and eight female zebra finch (Taeniopygia guttata) distance calls. These results do not indicate that chickadees have a species-specific advantage in individual recognition for conspecific over heterospecific vocalizations. We then transferred the chickadees to a discrimination of the same songs and calls rerecorded at a moderate distance. These results showed accurate transfer of discrimination from 16 vocalizations recorded at 5 m to novel versions of the same 16 songs and calls rerecorded at 25 m. That is, chickadees recognized individual songs and calls despite degradation produced by rerecording at 25 m. Identifying individual vocalizations despite their transformation by distance cues is here described as a biologically important example of perceptual constancy.     

Using MATLAB with the Psychophysics Toolbox to present the heterochromatic fusion nystagmus stimulus

We present a program for MATLAB that generates and presents theheterochromatic fusion nystagmus stimulus. This stimulus allows assessment of isoluminant states through recordings of reflexive eye movements (optokinetic nystagmus). The reflexive nature of the subject’s response makes this stimulus especially useful with nonverbal subjects, such as children and animals. Unfortunately, the stimulus is complex and difficult to program. By presenting the present program, we hope to help those who wish to use this tool in their research. The code of the function can be downloaded at www. dal.ca/~mcmullen/downloads.html.     

Developmental changes in source memory

Remembering how one learned a fact can be important in itself (e.g. for considering the value of information). However, source memory is also important, along with the temporal and perceptual information on which it is based, in giving memory an episodic or autobiographical quality. The present study investigated developmental changes in children’s ability to monitor source, in a paradigm adapted from Schacter, Harbluk and McLachlan (1984). This task, unlike previous source monitoring tasks used with children, has the potential to show the existence of a serious kind of source error called source amnesia. Children of 4, 6 and 8 years participated. They also completed measures believed to assess prefrontal function. Children showed a steady improvement with age in their ability to remember facts, but showed abrupt improvement between 4 and 6 years in their ability to monitor the source of those facts. Most notably, 4–year–old children displayed a great deal of source amnesia (i.e. errors of the kind committed by populations with frontal dysfunction), but 6– and 8–year–old children showed very few such errors. In addition, source memory was related, in some analyses although not in others, to behavioral measures often used to assess prefrontal functioning. The timing of the transition in source monitoring ability is discussed, including implications for childhood amnesia.     

Background beliefs in Bayesian inference

We report five experiments in which the role of background beliefs in social judgments of posterior probability was investigated. From a Bayesian perspective, people should combine prior probabilities (or base rates) and diagnostic evidence with equal weighting, although previous research shows that base rates are often underweighted. These experiments were designed so that either piece of information was supplied either by personal beliefs or by presented statistics, and regression analyses were performed on individual participants to assess the relative influence of information. We found that both prior probabilities and diagnostic information significantly influenced judgments, whether supplied by beliefs or by statistical information, but that belief-based information tended to dominate the judgments made.     

Mechanisms of source confusion and discounting in short-term priming: 1. Effects of prime duration and prime recognition

Huber, Shriffrin, Lyle, and Ruys (2001) measured short-term repetition priming effects in perceptual identification with two-alternative forced-choice testing. There was a preference to choose repeated words following passive viewing of primes and a preference against choosing repeated words following active responding to primes. In this present study, we explored conditions of prime processing that produce this pattern of results. Experiment 1 revealed that increased prime duration under passive viewing instructions produces the active priming pattern. Experiment 2 assessed memory for primes: With poor recognition of primes, there was a strong preference for repeated words; however, with good recognition of primes, this preference was eliminated. These results are modeled by a computational theory of optimal decision making, responding optimally with unknown sources of evidence (ROUSE). In ROUSE, a preference for repeated words results from source confusion between primes and choice words. A reversal in the direction of preference arises from the discounting of words known to have also appeared as primes.