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.     

The influence of stimulus uncertainty and experimental instructions on visual selection

The looking behavior of adults and children was recorded while they viewed pairs of stimuli differing in stimulus uncertainty. Ss in one experimental group were encouraged to identify the stimuli and indicate whether they had been seen in a previous phase of the experiment. For the remaining Ss, instructions minimized the importance of the stimuli to the experiment. Results indicate that, when stimulus uncertainty was influential, the relationship between stimulus uncertainty and looking time was monotonically increasing. However, stimulus uncertainty was an effective determinant of looking behavior only when Ss were motivated to identify the stimuli. The behavior of adults and children did not differ.     

Stimulus familiarity,dogmatism, and the duration of attention

Thirtyeight males and 30 females viewed each of 30 black and white photographs for as long as they wished. Half the photographs were judged by the Es to be unfamiliar to college students. The remaining photographs were judged to be familiar. After the looking task all Ss cotnpleted the Dogmatism Scale. It was predicted that the open-minded Ss would spend more time looking at the novel stimuli than the closed-minded Ss, and, that all Ss would spend more time looking at novel stimuli than familiar stimuli. The results failed to confirm the hypothesis that open-minded Ss would look longer at the novel stimuli than closed-minded Ss. However, it was found that Ss spent more time looking at novel stimuli than familiar stimuli regardless of the degree to which their belief systems were opened or closed. The adwwtage of manipulating stimulus familiarity by E-selection of the stimuli was discussed.     

The effects of instructions,fixed rate of presentation,and complexity on free looking time

The effect of stimulus complexity, prior experience with a short or long fixed rate of presentation (FRP) and S’s knowledge concerning the purpose ot the experiment on free looking time (FLT), was examined. Results indicated that under all conditions, Ss view complex stimuli longer than simple. A long FRP produced longer FLT than did a short FRP for Ss uninformed of the purpose of the experiment, hut FRP had no effect on FLT for Ss who were informed.     

Paired comparison scaling of reaction potential from simultaneous measurements of GSR and looking time

Thurstone’s method of scaling from paired comparison data was employed to obtain estimates of reaction potential on eight successive presentations of randomly generated polygons. One set of scale values was based upon the magnitude of the GSR made by each of 40 Ss to the onset of each stimulus. Another set of scale values was based upon the Ss looking times, when the S was instructed to press a switch to terminate the stimulus after he finished looking at it. Following termination of each stimulus, a 20-sec period of no stimulation intervened prior to the next stimulus. The GSR reduced in size from trial to trial, describing a typical habituation curve, while looking time increased from trial to trial. Across trials the two sets of scale values were significantly negatively correlated (r=?0.91). The failure to find habituation of looking time was explained on the assumption that the 20-sec period between stimuli was noxious to the Ss, which resulted in longer and longer looking times across trials. These results were interpreted as indicating that habituation of the GSR is not merely a matter of reduced attention in the cognitive sense. In addition, it was pointed out that the use of orienting reflex concepts in dealing with attentional and other cognitive phenomena may be unjustified.     

The effects of stimulus familiarization on patterns of visual selection

Patterns of visual selection were recorded as Ss viewed pairs of stimulus drawings in which the two members were either both incongruous or both banal. Prior to presenting the paired stimuli, S was preexposed to either one member of the stimulus pair or to the incongruous or banal counterpart of one member of the stimulus pair. The results indicate that: (1) preexposure to a stimulus reduced its potential to elicit looking responses, and the magnitude of that reduction was greater for incongruous stimuli than for banal stimuli; (2) preexposure to an incongruous stimulus affected the potential of its banal counterpart to elicit looking responses, but preexposure to a banal stimulus did not affect the potential of its incongruous counterpart to elicit similar responses; and (3) the reduced potential of the preexposed member of a stimulus pair to elicit looking responses waned after 10 sec. These results were discussed in light of an “information-conflict resolution” model of visual selection.     

The effects on eye movements of complexity,novelty, and affective tone

The major purpose of this study was to investigate the effects of stimulus complexity, novelty, and affective tone on the direction of eye movements of male college students. Motion pictures were taken of S’s eye while he viewed pairs of stimuli. In no instance, in any part of the 10 sec. viewing interval, did Ss as a group fixate longer on unpleasant stimuli when they were paired with either pleasant or neutral stimuli; and pleasant stimuli consistently dominated neutral stimuli. Also, novel stimuli and complex stimuli tended to dominate their non-novel and less complex competitors. Differences in instructions were found to markedly affect the magnitude but not the direction of fixation-dominance.     

Reliability of looking time

Twenty-eight college students viewed two sets of 30 color photographs each under instructions to look at each picture for as long as they wished. Equal thirds of the stimuli in each set were selected from high, middle, and low complexity levels. The sets were presented 7–10 weeks apart. The results indicated significant between- and within-session correlations that were not dependent on stimulus complexity. It was suggested that the findings were indicative of a consistency in either the rate at which Ss process information or the amount of information they process or both.     

The effect of rate of presentation

Two experiments investigated the effect of a pre-test series of pictures, presented at a fixed rate, upon Ss subsequent free looking time. The results indicated that high fixed rates of presentation (3 sec./presentation) reduced \ldnatural\rd looking times, and low fixed rates of presentation (15 or 60 sec./ presentation) increased natural looking times. The results were interpreted within an adaptation level theory framework. Accordingly, the fixed rate serves as an anchor which influences Ss \ldnatural\rd looking time. Evidence was also found suggesting that a simple imitation interpretation is questionable.     

The roles of practice and correction in the categorization of sour and bitter taste qualities

Ten Ss were selected from a group of 40 screened to determine misnaming of stimuli usually called sour (hydrochloric and citric acid) and bitter (quinine sulfate). The 10 Ss were then given 16 trials in which they were asked to match the stimuli to standards, with or without verbal feedback for each stimulus. This was followed by 16 trials without feedback for all Ss and, several days later, by a 16-trial posttest. Final improved performance of the Ss was not affected by having received the feedback. It was concluded that experience with the stimuli leads to a reduction in the degree of misnaming, implying a nonphysiological basis for sour-bitter confusions.     

On the Attention — Demand Value of Rorschach Stimuli

The attention-demand value of the Rorschach stimuli was investigated by measuring free looking time elicited by each card. Reports of content were not given by Ss. There were significant differences between cards in amount of looking which they elicited. This was closely related to judged complexity of the cards (r = .78) and response productivity of the cards under normal administration of the Rorschach test (r = .72). A comparison of looking times under two instructions, non-defensive and defensive, showed that the instructional variable tended to produce greater differences in looking time for some cards than for others. Cards low in complexity showed relatively longer looking times under the defensive conditions.     

Confidence ill stimulus predictions and choice reaction time

In two choice reaction time (RT) experiments, a stimulus prediction and a confidence judgment in the prediction preceded each occurrence of one of two stimulus alternatives. Ss identified each stimulus presentation by pressing a left-hand or right-hand telegraph key. In Experiment I the source of the stimulus predictions and confidence estimates was varied between groups of 20 Ss. For each condition, RT to correctly predicted stimuli was an inverse function of prediction confidence. Following incorrectly predicted stimuli, RT was not reliably influenced by confidence when S gave both predictions and confidence judgments; but RT to incorrectly predicted stimuli was an increasing function of confidence when E verbalized the predictions and confidence estimates or when S predicted and E indicated confidence. In Experiment II Ss made predictions and the validity of Es confidence estimate was manipulated between Ss. When Es confidence was perfectly related to the probability of a correct prediction, choice RT to nonpredicted stimuli was inversely related to confidence. However, choice RT to nonpredicted stimuli was not affected by prediction confidence when Es judgments were random.     

Human sensory dominance

Human Ss matched an auditory and a visual stimulus for subjective magnitude. Then each stimulus was used as a cue in a reaction time task. On occasions when both stimuli were presented simultaneously, Ss’ responding was seen to be dominated by the visual stimulus. Of further interest was the finding that on some occasions of simultaneous light-tone presentation Ss were unaware that the tone had been presented. This apparent prepotency of the visual over the auditory stimulus was seen to persist across a variety of experimental conditions, which included giving Ss verbal instructions to respond to the tone when both stimuli were presented simultaneously.     

Some determinants of looking time under different instructional sets

Four groups of Ss were asked to look at sets of figures whose members differed in degree of complexity and asymmetry. Ss instructed to look as long as the figures were pleasing did so for a significantly shorter time than did Ss who were instructed to look as long as they cared to, as long as the figures were interesting, or until they could recognize the figures in a large group of similar figures. Results indicated that looking time was affected by both the complexity and the asymmetry/symmetry dimensions and led to the conclusion that looking time is primarily a measure of exploratory behavior.     

Infants' recognition memory, forgetting, and savings.

In four experiments infants of 5–6 months of age were tested for recognition memory of briefly presented visual stimuli. In the first experiment infants showed relatively more looking at a novel picture when it was paired with a picture they had just studied for 10 or 20 sec. This differential response to novelty served as evidence of immediate recognition memory. In the second experiment these same 10- or 20-sec study times were used but were not sufficient to produce reliable evidence of memory over a long (48 hr) retention interval or even as short an interval as 40 sec. The third experiment demonstrated substantial delayed recognition if a brief reexposure of materials was introduced immediately prior to the recognition test. This reminder required less than the minimal study time found necessary to produce immediate recognition memory in Experiment 1. The results of the fourth experiment indicated that the savings effects that occurred in Experiment 3 were not solely due to familiarity with the testing procedures. The implications of savings effects in infants' memory are discussed.     

Effects of task difficulty on subsequent preference for visual complexity.

Ss rated on a 1 to 13 Likert scale their preference for four environmental scenes which differed in complexity. Ss were then given 30 sec. to solve each of 10 3-, 5-, or 7-letter single-solution anagrams. Finally the Ss rated four new slides which were of the same complexity level as the slides seen during the first session. Change scores were calculated by subtracting the preference ratings at each complexity level during the first session from the rating at the corresponding complexity level during the second session. The Anagram Complexity X Slide Complexity interaction was significant: the complexity of the slides showing the most positive change scores was inversely related to the complexity of the anagrams attempted. The results were discussed in terms of optimal level of stimulation theories.     

Immediate and long-term retention of basic-level categories in 24-month-olds

This study assessed the effect of presenting single versus multiple exemplars of basic-level categories on 24-month-olds' long-term memory for categorical information. Sixty-four infants were tested in a paired-comparison recognition memory paradigm immediately and one week after familiarization with basic-level categories. Infants were randomly assigned to one of two familiarization conditions and one of two test conditions. In one familiarization condition (Varied Exemplar), they briefly viewed four different exemplars of each of 16 basic-level categories. In the other familiarization condition (Single Exemplar), they viewed only one instance of each category on four different trials. Test trials consisted of either an exemplar seen during familiarization (Familiar-Exemplar Test) or novel intracategory exemplar (Unfamiliar-Exemplar Test) paired with a stimulus from a novel category. Both immediately following familiarization and one week later, infants looked longer at test stimuli from the novel category irrespective of familiarization or test condition.     

Time perception and word recognition: an elaboration of the time-criterion account

Past research suggests that a time criterion guides responding in speeded word recognition tasks. The time-criterion account has been challenged, however, because it incorrectly predicts equivalent latencies for stimuli of differing difficulty when those stimuli are presented in the same trial block. By requiring participants to perform a lexical decision or naming task but to respond only once they had estimated that 1 sec had elapsed, we investigated the idea that stimulus difficulty effects in response latency might be at least partially due to time perception processes. Consistent with this idea, the participants produced shorter estimates of 1-sec intervals when processing easier stimuli (i.e., time seemed to pass faster when easier stimuli were processed). The implication is that understanding speeded word recognition performance will require looking beyond processes involved in acquiring information about the presented stimulus and examining more general response processes.     

The effects of stimulus type,training, and chronological age on children's identification and recoding of multidimensional stimuli

Kindergarten and second-grade children (75 and 99 months of age, respectively) were first taught that the two stimuli within each of four pairs of multidimentional stimuli differed with respect to their values on every one of three bivalued dimensions: color, size, and form. Each of the eight stimuli was then presented twice, one at a time, and the child was asked either to find its duplicate (eight encoding trials) or to find its complementary mate (eight recoding trials) among the complete set of eight stimuli. Next, each of the eight stimulus compounds was presented twice as a display stimulus for 5 sec and, after a delay of 10 to 15 sec, the child was asked to find the display stimulus (eight trials of encoding plus memory) or its complement (eight trials of recoding plus memory) among the complete set. The stimuli for half the children in each age group were standard unitary compounds (e.g., a large red circle, a small blue square, etc.) and for the other half they were partitioned stimuli with their dimensional values spatially separated (e.g., large arrow, circle outline, and patch of color). Half of the children in each of these subgroups were given a basic pretraining, and the other half received extended pretraining, in recoding the stimulus attributes. The results indicated that unitary stimuli were easier to encode but the partitioned stimuli were easier to recode, that recoding was much more difficult than encoding, that extended training improved recoding performance, and that second graders were slightly better at encoding and much better at recoding than the kindergarten children. The patterns of performance on the tasks involving memory were similar to those just described. The results were discussed in terms of children's abilities to analyze multidimensional stimuli into their dimensional components.     

Free sorting with stimuli clustered in a multidlmensional attribute space

An experiment was conducted to determine whether Ss leam, without knowledge of results or prior familiarization with the prototypes, to sort histoform stimuli generated by three probablistic rules into categories consistent with these mies. Seven Ss were asked to sort 30 stimuli (10 from each schema population) on each trial. No constraints were placed on the number of categories to be used. A statistic was developed to measure consistency between schema-defined categories and subjeet-defined categories. Four of the seven Ss met the leaming criterion, and demonstrated increasing consistency with the schema-defined categories across trials. In general, more categories than necessary were used to classify the stimuli correctly. The results raise several questions about classification strategies used by Ss in perceptual learning tasks with stimuli generated by probabilistic rules, and indicate the need for further research conceming the variables that influence perceptual category formation.