The effects of complexity on the perception of vibrotactile patterns presented to separate fingers

Pairs of vibrotactile patterns were presented to subjects’ left middle and index fingerpads (unilateral presentation) or left and right index fingerpads (bilateral presentation), using two Optacon arrays. A set of simple (one-line) patterns and a set of complex (two-line) patterns were constructed sothat they were equally identifiable when presented individually. In Experiment 1, discrimination performance was lower for two-line patterns than it was for one-line patterns, and it was lower for unilateral presentation than it was for bilateral presentation. Communality, the number of lines that two patterns share in common, was a major factor in reducing discrimination performance for two-line patterns. Subjects’ abilities to identify one member of the pair of patterns were measured in Experiment 2. There were no significant differences in performance between pattern sets or type of presentation when subjects attended to a single pattern. However, when subjects were required to attend to both patterns, identification performance was lower for two-line patterns than it was for one-line patterns, and it was lower for unilateral presentation than it was for bilateral presentation. The results suggest that there are limited attentional resources for processing vibrotactile patterns and that more resources are available bilaterally than are available unilaterally.     

The effects of complexity on the perception of vibrotactile patterns.

Vibrotactile patterns were presented to subjects' left index fingerpads using the array from the Optacon. A set of simple (one-line) patterns and a set of complex (two-line) patterns were constructed so that they were equally identifiable when presented individually. In Experiment 1, discrimination performance was lower for two-line patterns than for one-line patterns. Communality, the number of lines that two patterns share in common, appeared to be the major factor in reducing discrimination performance for two-line patterns. Experiment 2 measured the time required to identify individual patterns. There was no significant difference in identification times for one- and two-line patterns, suggesting that features within a pattern were processed simultaneously. In the presence of a temporal masking stimulus (Experiment 3), two-line patterns were more difficult to identify than one-line patterns, but reaction times were similar for the two sets of patterns. The results suggest that varying complexity affects perception of patterns at later stages of processing.     

The effects of complexity on the perception of vibrotactile patterns

Vibrotactile patterns were presented to subjects’ left index fmgerpads using the array from the Optacon. A set of simple (one-line) patterns and a set of complex (two-line) patterns were constructed so that they were equally identifiable when presented individually. In Experiment 1, discrimination performance was lower for two-line patterns than for one-line patterns. Communality, the number of lines that two patterns share in common, appeared to be the major factor in reducing discrimination performance for two-line patterns. Experiment 2 measured the time required to identify individual patterns. There was no significant difference in identification times for one- and two-line patterns, suggesting that features within a pattern were processed simultaneously. In the presence of a temporal masking stimulus (Experiment 3), two-line patterns were more difficult to identify than one-line patterns, but reaction times were similar for the two sets of patterns. The results suggest that varying complexity affects perception of patterns at later stages of processing.     

The effects of a plastic-film covering on vibrotactile pattern perception with the Optacon

Three experiments were conducted to determine whether the perception of vibrotactile patterns presented to the fingertip on the Optacon (a reading machine for blind persons) would be affected by covering the array with a plastic membrane. Occasionally in psychophysical and physiological studies that involve the Optacon, the array is covered with a plastic film to minimize electrical transients during electrophysiological recording and to maintain cleanliness. In the three studies described here, observers performed a spatial acuity task, identified patterns of a previously learned set, and judged the loudness of vibrotactile noise patterns by means of absolute magnitude estimation, on both the covered and the uncovered-array. Performance in the spatial acuity and pattern identification tasks was not affected by the presence of the protective film. The rate of growth of perceived intensity was also the same with and without the plastic film, although there was a slight increase in vibrotactile detection threshold with the film.     

Tactile perception of sequentially presented spatial patterns

Tactile pattern recognition was studied by presenting pairs of alphabetic shapes in rapid succession at the same anatomical location, the subject being required on each trial to identify bath of the patterns. Experimental variables were the duration of each stimulus and the time between stimuli. Three aspects of the observed interaction were (1) an increase in letter reversals for very short interstimulus intervals; (2) a greater percentage of first-response errors for short-stimulus onset intervals and a greater percentage of second-response errors for long-stimulus onset intervals; and (3) a crossover in the first- and second-response error rates in the range of 100 to 200 msec. after the onset of the first stimulus. These results are consistent with some of the temporal properties of models proposed for analogous visual tasks.     

Lingual vibrotactile perception: lingual pressure effects on neuro-sensory response

A calibrated pressure transducer, embedded within a lower tongue clamp disk, enabled the application of specific tongue pressures during lingual threshold measurement. Thresholds were obtained for five tongue pressures (2, 5, 8, 11, and 14 PSIA ) at three frequencies (125, 250, and 500 Hz). Thresholds varied as a function of tongue pressure. As pressure increased from 2 to 8 PSIA thresholds decreased. As pressure increased above 8 PSIA thresholds increased. Tongue pressure did not influence frequency function.     

Visual perception of rapidly presented word sequences of varying complexity

Four experiments are described that determine whether or not syntactic complexity affects the visual perception of rapidly presented word sequences. The results indicate that sentences containing only one sentence in the underlying structure are more accurately reported than sentences containing two underlying sentences. It is shown that this result is not due solely to distortion of the input, but is likely to reflect the rate at which structural representations of the input can be developed.     

The effects of incongruity and complexity on the perception of humor

This study compared differing predictions about the relationship between subjects' style or preference for general cognitive complexity and the role of incongruity and complexity on the perception of humor. The subjects, all adult females, found simpler, less incongruous cartoons to be most humorous. Regardless of their general preference for cognitive complexity, ease of information processing seemed directly related to the perception of humor.     

The effect of location on the discrimination of spatial vibrotactile patterns

The present study examined whether the locations of patterns on the skin affected the ability to process information about their shapes. In Experiment 1, pairs of spatial vibrotactile patterns, using the array from the Optacon, were presented sequentially to subjects’ left index fingerpads. The location of each pattern in a pair was varied randomly among four locations on the skin. The subjects responded “same” or “different” on the basis of the shapes of patterns, regardless of their locations. Discrimination accuracy was highest and response time fastest when patterns occupied identical locations (ILs), and performance suffered with increasing distance between patterns. In Experiment 2, pairs were presented to corresponding points or to noncorresponding points on separate fingerpads. When patterns occupied corresponding points on separate fingers, accuracy was lower than when patterns occupied ILs on a single finger, but higher than when patterns occupied noncorresponding points on separate fingers. The results suggested that discriminability declined partly because patterns did not occupy ILs, and partly because separate locations had different densities of innervation.     

Temporal summation effects on lingual vibrotactile thresholds.

Ascending lingual vibrotactile thresholds at 250 Hz were obtained for four groups of normal-speaking adult subjects. Stimulus durations were varied for each respective group. Threshold values plotted as a function of stimulus duration indicated a temporal summation function occurring up to 200 msec. Findings are discussed in terms of underlying peripheral receptors and some implications for using summation measures as a basis for identifying oral sensory disorders.     

Some observations on the perception of Marroquin patterns.

Demonstrations are presented to show that the perception of structure in Marroquin patterns is disrupted if the dots comprising the pattern have opposite contrast polarity, and also if the dots comprising the pattern are separated in stereoscopic depth. It is also demonstrated that the perception of structure in a Marroquin pattern is made possible if the pattern is separated in stereoscopic depth from 'noise' dots, where the pattern structure cannot be perceived in either half of the unfused stereogram. In these respects the perception of Marroquin patterns is similar to the perception of Glass patterns. These findings are thus consistent with the proposal that the perception both of Marroquin and of Glass patterns is based on the construction of virtual lines.     

The effect of shape and location on temporal masking of spatial vibrotactile patterns

Target patterns presented to uncued locations on a single fingerpad were followed by either same-shape (SS) maskers or different-shape (DS) maskers presented to either the same location (SLoc) or a different location (DLoc). DS maskers interfered with identification more when they were at SLoc than when they were at Dloc, but the reverse was true for SS maskers; they interfered more at DLoc than at SLoc. When targets were presented to cued locations, performance in the absence of maskers improved, but the pattern of interference from maskers resembled that for uncued presentation. The proportion of masker responses on incorrect trials revealed that both temporal masking and response competition may be involved in the effects of location on pattern identification.     

Enhancement and summation in the perception of two successive vibrotactile stimuli

Enhancement and summation were found to be fundamentally different perceptual processes affecting the sensation magnitude of two successive vibrotactile stimuli. Enhancement, defined operationally as an increment in the subjective magnitude of one stimulus due to the presentation of a prior stimulus, and summation, defined as an increment in overall subjective magnitude of the two stimuli, were measured for sinusoidal vibration of the thenar eminence of the hand. The effect of summation was maximum when the two stimuli greatly differed in frequency, whereas maximum enhancement effects were found when both stimuli were close in frequency. The summation effect showed little decay as the interstimulus interval was increased to as much as 500 msec, whereas enhancement effects decayed to zero at approximately 500 msec. Results were similar to those obtained in comparable studies of audition and support the hypothesis that there are at least two distinct information-processing channels for the perception of cutaneous vibration.     

声调范畴感知和声调复杂度对音乐音高感知的跨领域影响

采用音高识别与区分任务, 以汉语母语者、越南语母语者和俄语母语者为研究对象, 考察了两个语言加工层面的因素, 即声调范畴感知模式以及不同语言声调系统的复杂度差异对跨领域音乐音高感知的影响。结果发现: (1)汉语和越南语两组声调语言母语者听辨结果符合范畴感知模式, 而俄语母语者是连续感知。在语言和音乐两种刺激条件下, 声调语言母语者在范畴边界宽度、范畴内区分率、范畴间区分率以及区分峰度等指标上不存在显著差异。(2)汉语和越南语两组声调语言母语者的音乐音高区分任务结果差异不显著。实验结果表明: 在行为层面, 母语声调范畴感知模式可以迁移到音乐音高感知中, 但复杂声调系统并不能促进跨领域的音乐音高精细感知。实验结果从语言对音乐音高加工影响的角度支持了“共享论”。     

The influence of chemical complexity on the perception of multicomponent odor mixtures

The present study investigates the hypothesis that complexobject odors (odors that emanate from flowers, foods, sewage, etc.) that consist of dozens of odorants are processed and encoded as discrete entities, as if each was a single chemical odor. To test this hypothesis, the capacity of trained subjects to discriminate and identify the components of stimuli consisting of one to eight object odors was determined. The results indicated that subjects could only identify up to four object odors in a mixture, which is similar to earlier findings with mixtures that contained only single chemical odors. The limited capacity was also reflected in the number of odors selected, regardless of whether the choices were correct or incorrect, in confidence ratings, and in decision times. The identification of a limited number of object odors in every mixture that was presented suggests that both associative (synthetic) and dissociative (analytic) processes are involved in the perceptual analysis of odor mixtures.     

The effects of intensity and interval rhythms on the perception of auditory and visual temporal patterns

Repeating temporal patterns were presented in the auditory and visual modalities so that: (a) all elements were of equal intensity and were equally spaced in time (uniform presentation); (b) the intensity of one element was increased (accent presentation); or (c) the interval between two elements was increased (pause presentation). Intensity and interval patterning serve to segment the element sequence into repeating patterns.

For uniform presentation, pattern organization was by pattern structure, with auditory identification being faster. For pause presentation, organization was by the pauses; both auditory and visual identification were twice as fast as for uniform presentation. For auditory accent presentation, organization was by pattern structure and identification was slower than for uniform presentation. In contrast, the organization of visual accent presentation was by accents and identification was faster than for uniform presentation. These results suggest that complex stimuli, in which elements are patterned along more than one sensory dimension, are perceptually unique and therefore their identification rests on the nature of each modality.