Stimulus complexity,free looking time,and inspective exploration

Fourteen Ss rated 59 objects on a seven point complexity scale. From these ratings 10 objects were chosen at the high, middle, and low levels of complexity, and 35 mm slides were made of these 30 objects. Fifteen Ss manipulated and inspected each of the objects for as long as they wished and a second group of 15 Ss viewed slides of the objects for as long as they wished. Analysis of the time scores from these two groups revealed that both inspective manipulation time and free looking time increased as a function of stimulus complexity. Inspective manipulation time was greater than free looking time except at the low complexity level.     

Stimulus proba]bility and choice reaction time

Two experiments, in which three stimuli were paired with two responses in a 2∶1, 1∶1 arrangement, showed choice RT to be a decreasing function of the relative frequency of stimulus occurrence when response frequencies are equated. The size of effect varied significantly with stimulus type (Experiment 1), being larger for circular light patches of differing diameter than for sets of colors, letters, and spatially distributed light sources, but was independent of differences in the similarity of stimulus alternatives within a set (Experiment 2). The results are discussed in terms of various strategies of stimulus identification.     

Stimulus complexity and choice inconsistency among gambles

Tversky (Psychological Review, 1969, 76, 31–48) found that some subjects can be induced to make intransitive choices among gambles. The gambles were so designed that for some pairs the subjects were inclined to choose on the basis of monetary values, while for others they were inclined to choose on the basis of the probabilities. This study replicates and expands Tversky's. The two principal findings are: (1) Tversky's results can be replicated using unselected subjects. (2) If subjects are forced to be transitive, by requiring them to evaluate the bets individually on a monetary scale, most resolve the intransitivity in favor of maximizing expected value.     

Stimulus complexity and prospective timing: clues for a parallel process model of time perception

Whereas many studies have considered the role of attention in prospective timing, fewer have established relations between movement complexity and prospective timing. The present study aims at assessing to what extent motion complexity interferes with prospective timing and at delineating a neuropsychophysical plausible model. We have thus designed a visual paradigm presenting stimuli in sequential pairs (reference comparison interval). Stimuli are motionless or moving according to different complexities, and stimulus complexities are intermixed within each pair. To prevent a possible attention-sharing effect, no concurrent task was required. Our study suggests that movement complexity is a key component of duration perception, and that the relative judgement of durations depends on spatio-temporal features of stimuli. In particular, it shows that movement complexity can bias subjects’ perception and performance, and that subjects detect that comparison intervals are longer than reference before their end. In the discussion, we advocate that the classical internal clock model cannot easily account for our results. Consequently, we propose a model for time perception, based on a parallel processing between comparison interval perception and the reconstruction of the reference duration.     

Word recognition under spatial transformation in retarded and normal readers

The recognition of words in normal, reversed, and inverted orientation was compared in a group of 9- to 11-year-old retarded readers and a matched group of normal readers. Using the ratio of reading times as an index of reading difficulty under spatial transformation, the results confirmed those of earlier studies which have shown that retarded readers' performance is less affected by spatial transformation than is normal readers'. However, an analysis in terms of the ratio of numbers of words read correctly pointed to just the opposite conclusion. The two sets of findings were reconciled by showing that they follow from the form of the function relating reading time to number correct, and by demonstrating that when word lists are equated for orthographic familiarity the performances of retarded and normal readers are equally affected by spatial transformation, whether the time or number ratio is used as an index.     

Stimulus and response prediction in choice reaction time: Free vs. forced reactions

Verbal predictions were combined in a 1:many mapping in order to analyze the contribution of response preparation to both stimulus and response prediction effects in choice reaction time (RT). Using a three-stimulus, two-response task in which two of the stimuli were mapped 1:1 to separate responses (forced-choice) and the third stimulus was mapped to both responses (free-choice), response frequencies and latencies were compared in two experiments. The results indicated that (1) free-choice response selections were not influenced by forced-choice stimulus predictions; (2) free-choice RTs were reduced only when the free-choice stimulus was correctly predicted; (3) free-choice responses were generally consistent with the response predicted, but RT did not depend on response prediction; (4) on forced-choice trials, the RT difference between correct and incorrect predictions was similar for stimulus and response predictions; and (5) under no-prediction conditions, no difference was found between free and forced RTs. A stimulus anticipation component was the only apparent contribution to the stimulus prediction effect, while the response prediction data suggest some prior response selection with no associated decrease in latency