Sensitivity of 5- and 7-month-old infants to pictorial depth information

An Ames (1951, Psychological Monographs, 65(1, Whole No. 324)) static trapezoidal window, under monocular view, was used to test young infants' responsiveness to pictorial depth. When adults view this display monocularly with the smaller side of the window rotated toward them, they report that the orientation of the display becomes ambiguous: When the head is moved, the window may appear to be in the fronto-parallel plane or either side may appear closer. The 7-month-olds we tested appeared to experience a similar ambiguity; they reached to the near side of the rotated trapezoidal window with significantly less consistency or directedness than infants in a control group tested with a rotated object that lacked pictorial depth information. When 5-month-olds were tested, however, they reached with equal consistency to the closer side of the trapezoidal window and of the control display, apparently uninfluenced by the pictorial depth information available in the trapezoidal window. Thus, sensitivity to the pictorial information for depth that is present in the trapezoidal window appears to develop after the age of 22 weeks.     

Imposed latencies,interruptions and dyadic interaction: Physiological response and interpersonal attraction

This study explored the impact of paralinguistic phenomena on interpersonal attraction and physiological measures during dyadic interaction. Conversations between undergraduate subjects and same-sex experimenters were either synchronous or asynchronous, with half the asynchronous conversations including imposed long latencies and the remainder frequent interruptions. Results showed that imposed latencies were associated with decreased positive attributions and greater physiological arousal, but interruptions had a moderately positive effect. The findings were discussed in terms of Chapple's theory of interaction, and their implications for psychotherapy and other interviews.     

Hemispheric asymmetries in faculty and student musicians and nonmusicians during melody recognition tasks

Current research has suggested that musical stimuli are processed in the right hemisphere except in musicians, in whom there is an increased involvement of the left hemisphere. The present study hypothesized that the more musical training persons receive, the more they will rely on an analytic/left-hemispheric processing strategy. The subjects were 10 faculty and 10 student musicians, and 10 faculty and 10 student nonmusicians. All subjects listened to a series of melodies (some recurring and some not) and excerpts (some actual and some not) in one ear and, after a rest, to a different series of melodies in the other ear. The task was to identify recurring vs. nonrecurring melodies and actual vs. nonactual excerpts. For student musicians, there was a right-ear/left-hemispheric advantage for melody recognition, while for student nonmusicians, the situation was the reverse. Neither faculty group showed any ear preference. There were no significant differences for excerpt recognition. Two possible explanations of the faculty performance were discussed in terms of physical maturation and a functionally more integrated hemispheric approach to the task.     

Naloxone and Pavlovian fear conditioning

Previous research has shown that pretreating rats with the opiate antagonist naloxone increases the freezing that follows painful electric shock. Three experiments, using freezing behavior as a dependent variable, were carried out to determine whether the drug might cause this effect by enhancing fear conditioning. Two of the studies employed a differential context fear-conditioning paradigm. Naloxone did not affect freezing behavior during the preshock adaptation period. In Experiment 1, naloxone was found to increase resistance to extinction in the S+ context. In Experiment 2, naloxone was found to increase freezing in the S+ context. This effect was dependent upon administering naloxone during training but not dependent on administering it during testing. The third study employed a generalization paradigm. It was found that naloxone's effect on postshock freezing was dependent on the place of testing; as the contextual cues of the test chamber were changed from those of the conditioning chamber, the effect of naloxone on freezing was reduced. The results of these experiments lend strong support to the hypothesis that naloxone increases freezing by enhancing the conditioning of fear to contextual stimuli associated with shock.     

Spontaneous configuring to a tone-light compound using appetitive training

Rats were trained to bar-press for water in the presence of a simultaneous compound tone-light stimulus using a discrete-trial procedure. Different groups were given between 300 and 3900 trials. When subsequently tested in extinction, all rats showed consistent levels of responding to the compound stimulus but responding to the tone and light components declined as a function of number of training trials. This is a demonstration of spontaneous configuring. Two other experiments showed that with similar procedures generalization from a component of the training stimulus to other values on the same continuum decreases with increased training with the compound stimulus. It was concluded that configuring and generalization from a single stimulus involve the same processes.     

Effect of delay-interval stimuli on delayed symbolic matching to sample in the pigeon

In Experiment 1, food-deprived pigeons received delayed symbolic matching to sample training in a darkened Skinner box. Trials began with the illumination of the grain feeder lamp (no food sample), or illumination of this lamp, accompanied by the raising of the feeder tray (food sample). After a delay of a few seconds, the two side response keys were illuminated, one with red and one with green light, with positions counterbalanced over trials. Pecking the red (green) comparison produced grain reinforcement if the trial had started with food (no food); pecking red after a no-food sample or green after a food sample was not reinforced. Once matching performance was stable, four stimuli were presented during the delay interval, and their effects on matching accuracy were evaluated. Both illumination of the houselight and the center key with white geometric forms decreased matching accuracy, whereas presentation of a tone and vibration of the test chamber did not. In Experiment 2, pecking the red center key was reinforced with food according to a variable interval schedule. The effects of occasional brief presentations of the four stimuli used in the first experiment on ongoing pecking were assessed. The houselight and form disturbed key pecking, but the tone and vibration did not. Thus, stimuli that interfered with delayed matching also interfered with simple operant behavior. Implications of these results for theories of remembering are discussed.     

A characterization of stochastic independence by association,with an application to random utility theory

A characterization of stochastic independence in terms of association of random variables is given. The result is applied to yield a simple proof of the Sattath-Tversky inequality without continuity assumptions.