Using video modeling and reinforcement to teach perspective-taking skills to children with autism

We evaluated video modeling and reinforcement for teaching perspective-taking skills to 3 children with autism using a multiple baseline design. Video modeling and reinforcement were effective; however, only 2 children were able to pass an untrained task, indicating limited generalization. The findings suggest that video modeling may be an effective technology for teaching perspective taking if researchers can continue to develop strategies for enhancing the generalization of these new skills.     

Bimanual interference associated with the selection of target locations

Four experiments were conducted to identify the locus of interference observed during the preparation of bimanual reaching movements. Target locations were specified by color, and the right-hand and left-hand targets could be either the same or a different color. Movements of different amplitudes (Experiment 1) or different directions (Experiment 2) to targets of the same color were initiated more quickly than symmetric movements to targets of different colors. These results indicate that costs observed during bimanual movements arise during target selection rather than during motor programming. Experiments 3 and 4 further examined the interference associated with target selection. Reaction time costs were found with unimanual movements when the target was presented among distractors associated with responses for the other hand. Interference observed during bimanual reaching appears to reflect difficulty in segregating the response rules assigned to each hand.     

Dissociations of personally significant and task-relevant distractors inside and outside the focus of attention: a combined behavioral and psychophysiological study

Studies of attentional capture by personally significant stimuli have reached inconsistent results, possibly because of improper control of the participants' attention. In the present study, the authors controlled visual attention by using a Stroop-like task. Participants responded to a central color and ignored a word presented either centrally (i.e., at the focus of attention) or peripherally (i.e., outside the focus of attention). Central words led to slower reaction times and larger orienting responses for significant items than for neutral items. These effects largely disappeared when the words appeared in a peripheral location. The peripheral words interfered with performance when they were relevant to task demands. These results indicate that there is a fundamental difference between task-relevant words and personally significant words: The former capture attention even when presented peripherally, whereas the latter do not.     

Semantic categorization in the human brain: spatiotemporal dynamics revealed by magnetoencephalography

We examined the cortical representation of semantic categorization using magnetic source imaging in a task that revealed both dissociations among superordinate categories and associations among different base-level concepts within these categories. Around 200 ms after stimulus onset, the spatiotemporal correlation of brain activity elicited by base-level concepts was greater within than across superordinate categories in the right temporal lobe. Unsupervised clustering of data showed similar categorization between 210 and 450 ms mainly in the left hemisphere. This pattern suggests that well-defined semantic categories are represented in spatially distinct, macroscopically separable neural networks, independent of physical stimulus properties. In contrast, a broader, task-required categorization (natural/man-made) was not evident in our data. The perceptual dynamics of the categorization process is initially evident in the extrastriate areas of the right hemisphere; this activation is followed by higher-level activity along the ventral processing stream, implicating primarily the left temporal lobe.     

Category variability, exemplar similarity, and perceptual classification

Experiments were conducted in which observers learned to classify simple perceptual stimuli into low-variability and high-variability categories. Similarities between objects were measured in independent psychological-scaling tasks. The results showed that observers classified transfer stimuli into the high-variability categories with greater probability than was predicted by a baseline version of an exemplar-similarity model. Qualitative evidence for the role of category variability on perceptual classification, which could not be explained in terms of the baseline exemplar-similarity model, was obtained as well. Possible accounts of the effects of category variability are considered in the General Discussion section.     

Learning new word meanings from context: a study of eye movements

This study examined how readers establish the meaning of a new word from the sentence context during silent reading. Readers' eye movements were monitored while they read pairs of sentences containing a target word, context, and a word related to the target word. The target word varied in familiarity (high, low, or novel). The context varied in informativeness about the meaning of the target word (informative or neutral). The amount of time readers spent on the context depended on both the familiarity of the target word and the informativeness of the context. Readers spent additional time on the related word only when the context was neutral and the target was novel. These results indicate that readers were able to determine which areas of text were relevant and used the information to infer a meaning for the novel word.     

The premack principle, response deprivation, and establishing operations

This paper describes response deprivation as an establishing operation. In this context, we review the concept of establishing operation, in particular, its reinforcer-establishing and evocative effects; we place response deprivation in the literature on the reinforcing effects of behavioral activity, wherein response deprivation subsumes the Premack principle; we describe the reinforcer-altering and evocative effects of response deprivation; and we address a methodological concern about the evocative effect. In closing, we discuss some conceptual and empirical implications of the foregoing analyses.     

How golden hamsters (Mesocricetus auratus) discriminate top from bottom flank scents in over-marks

Using a habituation-discrimination paradigm, the authors investigated what cues male golden hamsters (Mesocricetus auratus) use to determine the top and bottom positions in flank gland over-marks. A difference in the ages of 2 hamsters' marks did not, by itself, produce differential memory or evaluation of the 2 scents. A spatial configuration of marks suggestive of an overlap was sufficient for the apparently overlapping scent to be remembered or valued more than the apparently underlying scent. Cues from the overlap of 2 hamsters' marks were also sufficient. These results, consistent with those previously found for responses to hamster vaginal scent over-marks, suggest that hamsters use similar cues to analyze scent over-marks that are different in chemical composition and in social functions.