Stimulus suffix effects in recognition memory

Recall of auditory items can be disrupted by presentation of an irrelevant auditory stimulus (a stimulus suffix). Previous researchers have suggested that suffix effects are not found on recognition tests. Two experiments are presented here that demonstrate suffix effects on recognition tests. These results suggest that suffixes interfere with item information and that suffix effects cannot be attributed solely to retrieval processes.     

Stimulus duration as a measure of stimulus generalization

Four pigeons in the line-positive group were trained with a vertical line on a green background that signalled intermittent reinforcement while a plain green field signalled extinction. Four pigeons in the line-negative group were trained with the opposite discrimination. Response to a control key terminated any trial and initiated the next trial. The birds also used the control key during generalization tests to control the durations of trials in which various line orientations were presented. These durations were summed to provide generalization gradients of stimulus duration that were positive or negative in accordance with the trained discriminations. In Experiment 2, birds from the line-positive group were tested with a procedure in which the control key was not available on some trials. This provided an independent assessment of response rates to the test stimuli. These rates were used to predict the stimulus durations obtained when the control key was available. The findings supported a general model for the prediction of response distributions among concurrent stimuli from rates observed with single stimuli.     

Stimulus recognition and the mere exposure effect.

A meta-analysis of research on Zajonc's (1968) mere exposure effect indicated that stimuli perceived without awareness produce substantially larger exposure effects than do stimuli that are consciously perceived (Bornstein, 1989a). However, this finding has not been tested directly in the laboratory. Two experiments were conducted comparing the magnitude of the exposure effect produced by 5-ms (i.e., subliminal) stimuli and stimuli presented for longer durations (i.e., 500 ms). In both experiments, 5-ms stimuli produced significantly larger mere exposure effects than did 500-ms stimuli. These results were obtained for polygon (Experiment 1), Welsh figure (Experiment 2), and photograph stimuli (Experiments 1 and 2). Implications of these findings for theoretical models of the mere exposure effect are discussed.     

Stimulus selection with duration as a relevant cue

To date, research has not explicitly examined how duration competes with other stimulus dimensions for control over responding. The present study investigated some familiar selective mechanisms of stimulus control over key pecking in pigeons, with duration and line tilt as discriminative stimuli in successive discrimination procedures. Specifically, pigeon's key pecking was reinforced with food or extinguished following compound stimuli comprising one of two line orientation stimuli presented for one of two different durations. Traditional experimental designs explored stimulus additivity, overshadowing, blocking, and learned irrelevance. Although stimulus additivity was observed, control by duration was masked by line tilt in extinction testing that followed facilitated acquisition with redundant, relevant cues. In addition, although prior training with duration relevant partially blocked subsequent acquisition of control by line tilt when both stimulus dimensions were relevant, there was a tendency for control by duration to decrease with continued compound training. It was suggested that the greater time required to distinguish duration on a trial—compared to more commonly studied stimulus dimensions, which can be distinguished almost immediately—puts duration at a competitive disadvantage in situations where other relevant dimensions are also available.     

The Stimulus as a Series of Contexts for Practice

This study of concept attainment investigated the hypothesis that different forms of hypothesis (conjunctive/disjunctive) presented by the S would meet different arrays of contingencies. Sixty Ss, aged between 16 and 50, of both sexes, of various occupations, but all in the top 2% to 3% of the United Kingdom population in terms of intelligence, each attempted two concept-attainment problems, in the reception mode, with both attributes and form of concept unknown. The experimental material was that developed by Neisser and Weene, with concepts taken from their Level II. Instances were presented one by one on a typewritten sheet, on which the S was required to write an hypothesis after the presentation of each instance. Different types of contingency (positive and negative; confirming and infirming) differed in difficulty; different forms of hypothesis met characteristically different arrays of the four types of contingency. The results support the hypothesis above and call in question Bruner, Goodnow, and Austin's conclusion that the most important type of contingency is always the positive infirming.     

Stimulus information vs processing time in auditory pattern recognition

Previous studies have shown that pitch perception improves with increases in tone duration. An increase in tone duration increases the information available in the stimulus presentation. Other recent experiments have shown that sufficient perceptual processing time is also necessary for accurate pitch perception. The present study determines the relative contribution of stimulus information and processing time in an absolute pitch indentification task. The results indicate that processing time is more critical than stimulus information. The results are described accurately by a model that describes the perceptual process in terms of the information in the stimulus and the time the information is available for perceptual processing.     

Musical Preferences as a Function of Stimulus Complexity of Piano Jazz

Seven excerpts of modern jazz piano improvisations were selected to represent a range of perceived complexities. Audio recordings of the excerpts were played for 27 listeners who were asked to indicate their level of enjoyment on 7-point scales. Indications of enjoyment followed an inverted-U when plotted against perceived complexity of the music. Overall enjoyment was less for nonmusician listeners than for musician listeners. The inverted-U function was similar to the relations predicted by Wundt, over 100 years ago, and obtained by other investigators for responses to classical piano music and nonvocal New Age music. Assuming that perceived complexity generates comparable arousal levels, these findings substantiate optimal level of stimulation theory.