No reduction of spindle neuron number in frontoinsular cortex in autism

It has been suggested that spindle neurons, an evolutionarily unique type of neuron, might be involved in higher-order social, emotional, and cognitive functions. As such, it was hypothesized that these neurons may be particularly important to the pathophysiology of autism, a disease characterized in part by disruption of higher-order social and emotional processing. Therefore, we conducted the first stereological investigation of the number of spindle neurons in autism, using the optical fractionator technique. Our results did not provide evidence of a reduction in spindle neuron number in frontoinsular cortex in autism. However, this study provides the first quantitative stereological data on spindle neuron number in autism. Future postmortem studies with larger sample sizes will likely be critical in elucidating the spared and defective neural systems underlying the autistic phenotype.     

Navigating two-dimensional mazes: chimpanzees (Pan troglodytes) and capuchins (Cebus apella sp.) profit from experience differently

We examined whether navigation is impacted by experience in two species of nonhuman primates. Five chimpanzees (Pan troglodytes) and seven capuchin monkeys (Cebus apella) navigated a cursor, using a joystick, through two-dimensional mazes presented on a computer monitor. Subjects completed 192 mazes, each one time. Each maze contained one to five choices, and in up to three of these choices, the correct path required moving the cursor away from the Euclidean direction toward the goal. Some subjects completed these mazes in a random order (Random group); others in a fixed order by ascending number of choices and ascending number of turns away from goal (Ordered group). Chimpanzees in both groups performed equivalently, demonstrated fewer errors and a higher rate of self-correcting errors with increasing experience at solving the mazes, and made significantly fewer errors than capuchin monkeys. Capuchins were more sensitive to the mode of presentation than chimpanzees; monkeys in the Ordered group made fewer errors than monkeys in the Random group. However, capuchins’ performance across testing changed little, and they remained particularly susceptible to making errors when the correct path required moving away from the goal. Thus, these two species responded differently to the same spatial challenges and same learning contexts. The findings indicate that chimpanzees have a strong advantage in this task compared to capuchins, no matter how the task is presented. We suggest that differences between the species in the dynamic organization of attention and motor processes contribute to their differences in performance on this task, and predict similar differences in other tasks requiring, as this one does, sustained attention to a dynamic visual display and self-produced movements variably towards and away from a goal.     

When thoughts don’t feel like they used to: Changing feelings of subjective ease in judgments of the past

Thinking about the past is critical to everyday experiences, but people are not unbiased when doing so. Feelings of subjective ease that accompany generating reasons for known or alternative outcomes influence hindsight bias. But people do not always make decisions immediately after thinking about issues. Three experiments demonstrated that generating versus reading earlier generated reasons has markedly different effects on judgments, with theoretical and practical implications. Inevitability judgments were consistent with feelings of ease when generating reasons, but with numbers of reasons (content) when later reading those reasons. Experiments 2 and 3 also found that feelings of ease can be reconstructed if people reconsider their feelings when initially generating reasons. Discussion centers on the operation of subjective ease and its role in understanding judgment and decision making.     

Functional analysis and intervention of perseverative speech in students with high-functioning autism and related neurodevelopmental disabilities

Although perseverative speech is a common characteristic of individuals with high-functioning neurodevelopmental disabilities, little is known about the operant functions of these verbalizations. We conducted analogue functional analyses of perseverative speech for 2 students using reinforcement contingencies that included alone, attention, control, escape, and tangible conditions. Results showed the following patterns: attention only (Charlotte) or multiply determined including an attention function (Paul). We then tested an intervention for perseverative speech maintained by social positive reinforcement that included differential reinforcement of alternative behavior and extinction of perseverative speech for 1 participant. The intervention reduced perseverative speech, but did not increase appropriate speech until we added a prompting component. We then replicated this three-component intervention with Paul. The results showed moderate to high decreases in levels of perseverative speech and increased appropriate verbalizations in both cases. The results systematically replicated the interventions of previous studies by adding a prompting component to the intervention.     

Parafoveal processing in word recognition

Two experiments investigated the degree to which properties of a word presented in the parafovea influenced the time to process a word undergoing concurrent foveal inspection. In Experiment 1, subjects viewed a set of five-letter words at a fixed point, with words in parafoveal vision varying in length, word frequency, and both the type and token frequency of occurrence of their initial three letters. The results showed that the frequency of the target and the type frequency of its initial letters influenced foveal fixation time. In Experiment 2, subjects executed a sequence of saccades before initial fixation on the experimental items. Under these circumstances, fixation time was shorter overall. Lexical properties of parafoveal words had no effect on foveal processing, but the length and the type frequency of their initial letters exerted a strong influence. Parafoveal-on-foveal effects of this form are incompatible with models of reading in which attention is allocated sequentially to successive words. The data are more consistent with the proposition that foveal and parafoveal processing occurs in parallel, with processing distributed over a region larger than a single word. Subsidiary analyses showed little influence of any of the manipulated variables on saccade extent.     

Predictors of Teens' Attitudes Toward Condoms: Gender Differences in the Effects of Norms

Using data collected from a telephone survey of adolescents aged 15 to 19, we studied predictors of condom attitudes. Analyses were conducted on a sample of 348 sexually active teens. Multiple regression revealed that holding other variables constant being females, African American, perceiving that more of their friends were using condoms (i. e., perceived normative behavior). and stronger perceived normative pressure were significantly associated with favorable condom attitudes. Furthermore, significant interaction effects pointed to gender differences in the association between two types of norms and attitudes toward condoms. Perceived normative behavior had a greater effect on the attitudes of female adolescents. Perceived normative pressure had a greater effect on the attitudes of male adolescents.