Role of sex in externally motivated self-touching gestures

Self-touching gestures can be externally induced by the verbal presentation of anxiety-inducing stimuli and the active discussion of a passage. The frequency of these self-touching gestures appears to be affected by the individual interacting with the topic, the type of discourse (listening or discussing), the type of stimulus (canaries or leeches), and the interaction between the types of discourse and stimulus. This study assessed these variables as well as the sex of the participant and the order of presentation of stimulus type, neither of which were statistically significant. Participants were read two passages, one about a topic (leeches) expected to produce anxiety and the other about a topic (canaries) not expected to do so, and asked to answer questions about the passages. The number of self-touches was counted by an observer in another room. Each participant had both types of discourse (listening and discussing) and both types of stimulus (canaries and leeches). There was no significant difference between the number of self-touches by participants with either the male or female reader. Discussion as a method of discourse was associated with a significantly greater number of self-touches than listening. The interaction between discourse type and stimulus type was also significant. The combination of the anxiety-producing stimulus and the active discourse (discussion) produced the highest average number of self-touches.     

The development of causal categorization

Two experiments examined the impact of causal relations between features on categorization in 5- to 6-year-old children and adults. Participants learned artificial categories containing instances with causally related features and noncausal features. They then selected the most likely category member from a series of novel test pairs. Classification patterns and logistic regression were used to diagnose the presence of independent effects of causal coherence, causal status, and relational centrality. Adult classification was driven primarily by coherence when causal links were deterministic (Experiment 1) but showed additional influences of causal status when links were probabilistic (Experiment 2). Children's classification was based primarily on causal coherence in both cases. There was no effect of relational centrality in either age group. These results suggest that the generative model (Rehder, 2003a) provides a good account of causal categorization in children as well as adults.     

The effects of context change on long-term habituation of the orienting response in humans

Four experiments examined the effects of context change (Experiments 1-3) and context extinction (Experiment 4) on long-term habituation of the skin conductance response. In all experiments, subjects received 15 presentations of a target stimulus in each of two sessions. In Experiment 1 (N=60) there was a 15-min interval between training and test sessions. This interval was extended to 24 hours in Experiments 2 (N=60) and 3 (N=60). The experimental treatment in each of these studies involved a change in context between the two training sessions. None of the experiments provided evidence of context dependency in measures of long-term habituation. In Experiment 4 (N=60) experimental subjects received a period of context extinction during which they remained in the laboratory environment between two series of habituation trials. Again, however, there was no evidence that long-term habituation was contextually mediated. Thus, the results fail uniformly to support theories that argue that long-term habituation is context-dependent.