Effects of stimulus complexity on mental rotation rate of polygons

Both spatial and propositional theories of imagery predict that the rate at which mental images can be rotated is slower the more complex the stimulus. Four experiments (three published and one unpublished) testing that hypothesis found no effect of complexity on rotation rate. It is argued that despite continued methodological improvements, subjects in the conditions of greater complexity may have found it sufficient to rotate only partial images, thereby vitiating the prediction. The two experiments reported here are based on the idea of making the discriminative response sufficiently difficult so as to force the rotation of complete images. The first one scaled the similarity between standard polygons and certain systematically mutated versions. From the ratings so obtained, two levels of perceived similarity, high and low, were defined and served as separate conditions in a response-time, image rotation experiment. The second experiment tested the complexity hypothesis by examining the effect of similarity on rotation rates and its interaction with levels of complexity. The results support the complexity hypothesis, but only for the highly similar stimuli. Rotation times were also generally slower for high as compared with low similarity. It is argued that these results arise because subjects rotate incomplete images when the stimuli are not very similar.     

Effects of irrelevant spatial S-R compatibility depend on stimulus complexity

Summary Choice-reaction time is known to depend on the spatial correspondence of stimulus and response, even if the stimulus location is irrelevant to the task (Simon effect). An experiment investigated whether this effect depends on stimulus complexity — i. e., on whether properties of the stimulus render stimulus discrimination easy or difficult. It was hypothesized that high demands on discrimination slow down the processing of stimulus identity in relation to location, so that the facilitating or conflicting location code has more time to decay, thus losing impact on response selection. In fact, the results revealed an effect of irrelevant spatial S-R correspondence with easy, but not with difficult, stimulus discrimination. This finding resolves an apparent contradiction between the results of several previous experiments on the Simon effect.The other central argument rests on findings of Stoffer (1991) obtained with a single frame. These, however, have recently been challenged by Hommel (1993 b).     

Amount of stimulus exploration and preference as differential functions of stimulus complexity

Two sets of photographic slides, one made up of scenes from the geographic environment, the other of works of non-representational modern art, were scaled for complexity by obtaining judges’ ratings of amount of variation present on several specified stimulus attributes. Fourteen slides defining a sevenpoint scale of complexity were selected from each set and given to college students to obtain measures of (a) amount of exploratory behavior (number of times S chose to expose each slide briefly), and (b) preference (evaluative ratings on a seven-point scale). In accordance with prediction, the former measure emerged as a linearly increasing function of complexity, while the relationship between complexity and preference was curvilinear, reaching a maximum at an intermediate level of complexity. The results are related to Berlyne’s distinction between specific and diversive stimulus exploration, and implications for the study of aesthetics are discussed.     

Visual complexity and stimulus pacing in chicks

Two groups were tested for spontaneous alternation using massed and spaced trials but alternation rate was not above chance level. Two experiments then examined the use of visual stimuli as pacers for an approach response. The results indicate that subjects responded to complexity and that complexity may be a more effective pacer than novelty.     

Perceived stimulus complexity and food preference development

The importance of perceived complexity, a "collative property" as defined by [Berlyne, D. E. (1967). Arousal and reinforcement. In Nebraska symposium on motivation (pp. 1-110). University of Nebraska Press], to the dynamic development of preference was investigated. Eighty-six female and 82 male subjects rated their liking for and various collative properties of seven very similar orange drinks that differed only in perceived complexity as a result of adding small quantities of other flavours. This was done before and after giving each subject extended experience of one of the drinks, each being used equally often for this purpose. As predicted by the theory of [Dember, W. N., & Earl, R. W. (1957). Analysis of exploratory, manipulatory and curiosity behavior. Psychological Review, 64 (2), 91-96] exposure to a stimulus with a slightly higher complexity than an individual subject's optimally preferred level of perceived complexity, caused an upwards shift in that level, whereas exposure to a less complex stimulus had no such effect. Changes in the appreciation of the drinks predicted by the theory were also observed.     

Looking time: The effects of stimulus complexity and familiarity

During a 10 min. stimulus familiarization period, three groups of 60 Ss each received either 0, 10, or 20 sec. of familiarization on each of 30 experimental stimuli: 10 each of low, medium, and high stimulus complexity. All Ss then viewed the experimental stimuli in a second task, during which they could look at each stimulus for as long as they wished (free looking). For half the Ss in each group, free looking was administered immediately after the familiarization period. The remaining Ss received free looking 48 hr. later. The results replicated earlier research which has shown that free looking time is inversely related to stimulus familiarity, and directly related to stimulus complexity. Unlike earlier findings, the data suggested that with a 48 hr. delay between familiarization and free looking, a stimulus can, at least partially, recover from the decrement in looking time produced by 10 sec. of familiarization.     

Effects of two levels of stimulus complexity upon hypothesis sampling systems among second and sixth grade children

Groups of second and sixth grade children each solved a series of discrimination-learning problems involving four and eight dimensions that contained blanktrial probes for the S′s hypothesis (H). There were significant effects of grade level on three dependent measures (learning, generating consistent H patterns, sampling locally consistent Hs). Main effects of stimulus complexity were significant on five measures (the three above, rejecting disconfirmed Hs, maintaining confirmed Hs). There were no interactions involving any of these measures. The hypothesis sampling system (Sy) observed in each problem was also determined. Among sixth grade Ss this measure was unaffected by stimulus complexity level. Second grade Ss generated logically structured Sys in 65% of four-dimensional, but only 30% of eight-dimensional problems. They generated stereotyped behaviors or unsystematic sequences of Hs in 70% of eight-dimensional, but only about 35% of four-dimensional problems. Detailed analyses revealed that among second grade Ss good information processors (in terms of four component processes above) usually imposed a logical structure on four-dimensional, but generated unsystematic sequences of Hs in many of eight-dimensional problems. Poor processors generated stereotyped behaviors in both four- and eight-dimensional problems.     

Duration of visible persistence in relation to stimulus complexity

Visible persistence refers to the phenomenal impression that a stimulus is still present after its offset. A dispute exists whether visible persistence is due to temporal sluggishness in the visual pathway (neural hypothesis) or whether it is a byproduct of information-extraction processes under cognitive control (process hypothesis). This was investigated by manipulating stimulus complexity in five temporal integration experiments and one recognition memory experiment. According to the process hypothesis, complex stimuli should persist longer than simple stimuli because they require more information extraction. This prediction was not confirmed; in all six experiments, complexity was found to have no reliable effect on the duration of visible persistence. By contrast, and in accordance with earlier findings, complexity was shown to have a significant effect on a short-lived, nonvisible form of memory known as schematic persistence. This pattern of results supports two major conclusions: First, that the effects of complexity reported in earlier research were probably on schematic—rather than visible—persistence; and second, that visible persistence must be regarded as a residual neural trace of an extinguished stimulus, rather than as a byproduct of information-extraction processes.     

Note on preference for stimulus complexity across the life-span

Preference for stimulus complexity across the life-span was investigated with 175 females ranging in age from 17 to 72 yr. of age. Preference for complexity appeared to be age-invariant and monotonic function. Relationships to previous findings are discussed.     

Duration of visible persistence in relation to stimulus complexity.

Visible persistence refers to the phenomenal impression that a stimulus is still present after its offset. A dispute exists whether visible persistence is due to temporal sluggishness in the visual pathway (neural hypothesis) or whether it is a byproduct of information-extraction processes under cognitive control (process hypothesis). This was investigated by manipulating stimulus complexity in five temporal integration experiments and one recognition memory experiment. According to the process hypothesis, complex stimuli should persist longer than simple stimuli because they require more information extraction. This prediction was not confirmed; in all six experiments, complexity was found to have no reliable effect on the duration of visible persistence. By contrast, and in accordance with earlier findings, complexity was shown to have a significant effect on a short-lived, nonvisible form of memory known as schematic persistenc. This pattern of results supports two major conclusions: First, that the effects of complexity reported in earlier research were probably on schematic--rather than visible--persistence; and second, that visible persistence must be regarded as a residual neural trace of an extinguished stimulus, rather than as a byproduct of information-extraction processes.     

Effects of dispositional self-focus,appraisal and attention instructions on responses to a threatening stimulus

Abstract

Two studies are reported which explored the relationship between self-focused attention and anxiety. The first study tested the hypotheses that self-focused attention is associated with anxiety in threatening situations and that the relationship is mediated by negative appraisal processes. Study 1 showed no significant interaction between self-focus and negative appraisal on state-anxiety. However, self-focus was associated with increments in state-anxiety, high levels of worry and somatic symptom reports in a threatening situation. The relationship between self-focus and state-anxiety was mediated by somatic symptoms. Study 2 used cognitive and somatic self-attention instructions and external focus instructions to verify the hypothesis that self-focus on somatic arousal is associated with anxiety. It is concluded that specific self-focusing tendencies are associated with the elicitation and exacerbation of anxiety.     

Effects of an emotional negative stimulus on the cardiac, electrogastrographic, and respiratory responses

The experiment investigated the effects of two film sequences, one neutral and the other emotional, on the cardiac (ECG), electrogastrographic (EGG) and respiratory activities of 24 healthy students during digestion. The physiological activity was recorded before and during the projection of each film sequence. 12 subjects were shown a neutral film sequence and 12 an emotional film sequence. At the end of each viewing period, each subject completed a self-rating questionnaire on the emotional experience. Analysis indicated, with respect to the previewing (baseline) values, an increase in cardiac and respiratory rates and a decrease in electrogastrographic rates during the viewing of the film sequences. Changes in the EGG rate (baseline to viewing) were negatively correlated with the changes in ECG and respiratory rates, whereas the changes in these latter two were positively correlated. In comparing the effects of the neutral and emotional scenes the only significant result was the heart-rate increase in subjects watching the emotional sequence. Also, the self-rating of emotional experience varied with the emotional value of the sequence.     

Effects of stimulus probability and visual similarity on stimulus encoding

Visual similarity, stimulus probability, and stimulus contrast were manipulated in two memory-scanning experiments to determine how stimulus probability affects encoding. Two hypotheses were tested: The first, a featural facilitation hypothesis, localizes the effect of stimulus probability on feature extraction; the second claims that stimulus probability has its effect on stimulus recognition. In both experiments, visual similarity was found to slow encoding, particularly under low-contrast conditions. This effect was larger for low probability stimuli than for high probability stimuli and increased as the difference in probability between two visually similar stimuli increased. These results are inconsistent with the featural facilitation hypothesis, but can be explained in terms of differential priming of internal recognition responses for members of the stimulus set, such that more probable members are more easily recognized.