A "unity assumption" does not promote intersensory integration

An account of intersensory integration is premised on knowing that different sensory inputs arise from the same object. Could, however, the combination of the inputs be impaired although the "unity assumption" holds? Forty observers viewed a square through a minifying (50%) lens while they simultaneously touched the square. Half could see and half could not see their haptic explorations of the square. Both groups, however, had reason to believe that they were touching and viewing the same square. Subsequent matches of the inspected square were mutually biased by touch and vision when the exploratory movements were visible. However, the matches were biased in the direction of the square's haptic size when observers could not see their exploratory movements. This impaired integration without the visible haptic explorations suggests that the unity assumption alone is not enough to promote intersensory integration.     

A test battery to assess intrasensory and intersensory development of young children.

The purpose of the study was to develop a battery of tests for use in evaluation of intra- and intersensory development of young children. A battery of 15 tests (4 visual, 4 auditory, 4 tactile-kinesthetic, and 3 intersensory) was administered to 109 normally developing 6- and 8-year-old and 32 slowly developing or learning disabled children. Interdependence of test items within each intrasensory and the intersensory category was determined; intercorrelations ranged from .00 to .78. Reliability estimates were also determined. Face validity was claimed for each item. The effects of age or developmental level on test performance were established. Based upon the interdependence of the tests, reliability estimates, and the capacity of the tests to discriminate among groups classified according to age or developmental level, a battery of 10 intra- and intersensory tests was proposed. The battery has 3 tests of visual perception-visual memory, dynamic depth perception, and size discrimination; 3 tests of auditory perception-auditory discrimination, auditory memory of related syllables, and auditory sequential memory of numbers; 2 tests of tactile-kinesthetic perception-tactile integration and movement awareness; and 2 tests of intersensory integration-auditory-tactile intergration and auditory-visual integration.     

GSR amplitude instead of GSR magnitude: Caveat emptor!

Size of GSR made by 300 Ss to 20 repetitions of a visual stimulus is presented as mean magnitude and mean amplitude, illustrating that the amplitude method (averaging only those responses which are greater than zero) is susceptible to distortion resulting from a systematic elimination of Ss who initially make small responses. From trial to trial, the amplitude function comes more and more to be due to the behavior of Ss who initially make large responses. Even though the latter Ss’ responses actually reduce across trials, the amplitude function rises. Magnitude (including zeroes) docs not suffer from this distortion. It is suggested that the definition of a zero response is the source of the problem.     

Automatizing of visual attention

Perceptual automatizing was argued to occur as a consequence of repeated experience with a stimulus. Automatizing was hypothesized to entail a stereotyping in sampling of sensory information together with an attendant decrease in the rate of sampling of that information. An experiment was performed in which human Ss observed stimulus pictures for several trials, during which records were made of their visual fixations. It was found that fixation rate habituated and that this habituation was accompanied by a reduction in the uncertainty (entropy) of the spatial distributions of fixations. These results were interpreted as evidence for automatizing of visual fixation processes. Analysis of eye-movement distances suggested a possible mechanism for the reported loss of vividness of a stimulus which is perceived habitually.     

Behavioral Differences between Rabbits and Cats

The sensory modality of a task and the modality of a retroactive interfering activity were systematically covaried in order to test Connolly and Jones' and Pick's translation models of intersensory functioning. Forty 10-year-old boys and girls were asked to recall distance and location cues of length under intrasensory and intersensory task conditions (visual and kinesthetic). Visual and kinesthetic interpolated activities were used in an attempt to provide modality specific interference with the recall of length under the various sensory task conditions. Results of the data analyses provided no support for the Connolly and Jones model of modality specific storage with translation. Rather, the findings of the study were interpreted as supportive of Pick's hypothesis which emphasizes the coding of stimulus information (regardless of modality of input) into a form specific to whatever modality is specialized for detection of the information.     

How bumblebees first find flowers: Habituation of visual pattern preferences, spontaneous recovery, and dishabituation

Two experiments examined the exploratory behaviour of flower-naïve bumblebees. Bees were tested four times in a 12-arm radial arm maze in which they never received reward. Patterned and unpatterned stimuli were presented at the end of each corridor and the choices of the bees were recorded. We examined the effects of two variables, time and the presentation of a new stimulus, on habituation to a visual pattern. In Experiment 1, once bees had shown an unlearned preference for a pattern, and the preference had habituated, a response decrement was maintained after a confinement in the colony of two hours. After a 24 h confinement, however, the pattern preference was restored, i.e., spontaneous recovery was observed. In Experiment 2, the presentation of a new stimulus triggered renewed responding to the old pattern to which the bees had habituated, i.e., dishabituation was observed. Habituation to visual patterns is modulated by time and by exposure to new stimuli so that exploration in the face of failure to find food persists and unrewarding visual patterns are not eliminated for long as possible sources of food.     

Stimulus novelty and intraseries primacy in GSR adaptation

GSR records were obtained for four groups of 20 Ss. Group I was presented with a series of four different lights (amber, blue, green, and white) appearing 20 times each, in apparent random order. The procedure was similar for the other three groups except that in group 2, a novel stimulus (a red light) appeared instead of the sixth amber light; in group 3, it appeared instead of the 16th amber light; and, in group 4, it appeared instead of the 16th amber light. Typical GSR adaptation phenomena were observed in all groups. The introduction of the novel stimulus appeared to have no effect on the course of GSR adaptation.     

Intersensory conflict between vision and touch: the response modality dominates when precise, attention-riveting judgments are required

In four experiments, reducing lenses were used to minify vision and generate intersensory size conflicts between vision and touch. Subjects made size judgments, using either visual matching or haptic matching. In visual matching, the subjects chose from a set of visible squares that progressively increased in size. In haptic matching, the subjects selected matches from an array of tangible wooden squares. In Experiment 1, it was found that neither sense dominated when subjects exposed to an intersensory discrepancy made their size estimates by using either visual matching or haptic matching. Size judgments were nearly indentical for conflict subjects making visual or haptic matches. Thus, matching modality did not matter in Experiment 1. In Experiment 2, it was found that subjects were influenced by the sight of their hands, which led to increases in the magnitude of their size judgments. Sight of the hands produced more accurate judgments, with subjects being better able to compensate for the illusory effects of the reducing lens. In two additional experiments, it was found that when more precise judgments were required and subjects had to generate their own size estimates, the response modality dominated. Thus, vision dominated in Experiment 3, where size judgments derived from viewing a metric ruler, whereas touch dominated in Experiment 4, where subjects made size estimates with a pincers posture of their hands. It is suggested that matching procedures are inadequate for assessing intersensory dominance relations. These results qualify the position (Hershberger & Misceo, 1996) that the modality of size estimates influences the resolution of intersensory conflicts. Only when required to self-generate more precise judgments did subjects rely on one sense, either vision or touch. Thus, task and attentional requirements influence dominance relations, and vision does not invariably prevail over touch.     

Stimulus novelty and intraseries primacy in GSR adaptation

GSR records were obtained for four groups of 20 Ss. Group I was presented with a series of four different lights (amber, blue, green, and white) appearing 20 times each, in apparent random order. The procedure was similar for the other three groups except that in group 2, a novel stimulus (a red light) appeared instead of the sixth amber light; in group 3, it appeared instead of the 11th amber light; and, in group 4, it appeared instead of the 16th amber light. Typical GSR adaptation phenomena were observed in all groups. The introduction of the novel stimulus appeared to have no effect on the course of GSR adaptation.     

Late‐ but not early‐onset blindness impairs the development of audio‐haptic multisensory integration

Integrating different senses to reduce sensory uncertainty and increase perceptual precision can have an important compensatory function for individuals with visual impairment and blindness. However, how visual impairment and blindness impact the development of optimal multisensory integration in the remaining senses is currently unknown. Here we first examined how audio‐haptic integration develops and changes across the life span in 92 sighted (blindfolded) individuals between 7 and 70 years of age. We used a child‐friendly task in which participants had to discriminate different object sizes by touching them and/or listening to them. We assessed whether audio‐haptic performance resulted in a reduction of perceptual uncertainty compared to auditory‐only and haptic‐only performance as predicted by maximum‐likelihood estimation model. We then compared how this ability develops in 28 children and adults with different levels of visual experience, focussing on low‐vision individuals and blind individuals that lost their sight at different ages during development. Our results show that in sighted individuals, adult‐like audio‐haptic integration develops around 13–15 years of age, and remains stable until late adulthood. While early‐blind individuals, even at the youngest ages, integrate audio‐haptic information in an optimal fashion, late‐blind individuals do not. Optimal integration in low‐vision individuals follows a similar developmental trajectory as that of sighted individuals. These findings demonstrate that visual experience is not necessary for optimal audio‐haptic integration to emerge, but that consistency of sensory information across development is key for the functional outcome of optimal multisensory integration.     

A two-stage model for visual-auditory interaction in saccadic latencies

In two experiments, saccadic response time (SRT) for eye movements toward visual target stimuli at different horizontal positions was measured under simultaneous or near-simultaneous presentation of an auditory nontarget (distractor). The horizontal position of the auditory signal was varied, using a virtual auditory environment setup. Mean SRT to a visual target increased with distance to the auditory nontarget and with delay of the onset of the auditory signal relative to the onset of the visual stimulus. A stochastic model is presented that distinguishes a peripheral processing stage with separate parallel activation by visual and auditory information from a central processing stage at which intersensory integration takes place. Two model versions differing with respect to the role of the auditory distractors are tested against the SRT data.     

Active detection of solid-shape information by touch and vision

Five groups of Ss were tested under conditions of intra- and intermodal equivalence matching for free-form unfamiliar shapes originally designed by Gibson. Findings indicated that visual intramodal matching was superior to intermodal matching, a result consistent with previous research. The order of accuracy in forming equivalence was: (1) intramodel visual, (2) intramodal haptic, (3) haptic to visual, (4) visual to haptic. A difference, but not a significant one, in accuracy occurred for intramodal haptic matching when Ss wore goggles and when they did not.     

Sleep and overextinction of the GSR component of the orienting response

Overextinction of the GSR component of the orienting response was examined in a sample of 68 socially disturbed adolescents. Continued stimulus repetition beyond the point of habituation resulted in GSR return after 50–60 stimulus presentations. However, division of Ss into sleep and non-sleep groups using behavioral and self-report criteria, failed to support Sokolov’s (1963) notion that overextinction is accompanied by drowsiness. A possible explanation of these results is discussed.     

Attention-dependent visual capture in double vision

When the visual image of a body part, such as a finger, is doubled by a prism, the 'felt' position of that body part is captured by one of its visual images. Moving eye fixation from one to the other visual image is accompanied by a quick shift of the felt position. When focal attention is dissociated from foveation, the former determines visual capture. These new observations underline an active role of focal attention in intersensory integration and sensory-motor coordination of body parts.     

Visual size perception and haptic calibration during development

It is still unclear how the visual system perceives accurately the size of objects at different distances. One suggestion, dating back to Berkeley’s famous essay, is that vision is calibrated by touch. If so, we may expect different mechanisms involved for near, reachable distances and far, unreachable distances. To study how the haptic system calibrates vision we measured size constancy in children (from 6 to 16 years of age) and adults, at various distances. At all ages, accuracy of the visual size perception changes with distance, and is almost veridical inside the haptic workspace, in agreement with the idea that the haptic system acts to calibrate visual size perception. Outside this space, systematic errors occurred, which varied with age. Adults tended to overestimate visual size of distant objects (over‐compensation for distance), while children younger than 14 underestimated their size (under‐compensation). At 16 years of age there seemed to be a transition point, with veridical perception of distant objects. When young subjects were allowed to touch the object inside the haptic workspace, the visual biases disappeared, while older subjects showed multisensory integration. All results are consistent with the idea that the haptic system can be used to calibrate visual size perception during development, more effectively within than outside the haptic workspace, and that the calibration mechanisms are different in children than in adults.     

Overextinction of the orienting reaction

Sokolov’s 1963 report of return of the orienting reaction (OR) to repeated stimulus presentations following habituation was examined in 18 S’s using the galvanic skin response (GSR) component of the OR and an auditory stimulus of 60 db intensity and 1000 cps. Both group and individual S data analysis indicated a return of the OR which habituated quickly. The number of stimulus presentations to the OR return point showed an inverse relationship to rate of initial OR habituation for individual S’s.     

The effect of change in sequential visual stimuli on GSR adaptation: II,the novel stimulus as a disinhibiting stimulus

GSR records were obtained for 20 Ss presented with a series of 80 stimuli (four lights alternating in apparent random sequence). Records were obtained, also, for 20 Ss in each of two groups, using the same procedure: in Group 1, a tone was substituted for one of the lights, early in the sequence, and in Group 2, it was substituted later in the sequence. The tone, the novel stimulus, produced significant changes in the GSR adaptation patterns of the two groups.     

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.     

Intermodal enhancement of stimulus localisation in infants born prematurely

The interaction of auditory and visual modalities in the enhancement of orientation was examined in premature and near-term infants by presenting them auditory or visual stimuli or auditory-visual stimulus combinations at various positions in sensory space. In 4.5--15-mo-olds, brisk orienting responses could be elicited to very peripheral stimulus positions but only when the stimulus consisted of a spatially coherent auditory-visual combination (i.e., where a sound and a light occurred at the same point in space). This occurred for all infants, irrespective of age or gestational age at birth. First, the result shows that infants can respond to visual stimuli at eccentric positions, beyond the supposed limits of their effective visual fields as measured by standard perimetry. Second, the result extends earlier studies showing that intersensory integration and stimulus localisation develop relatively normally in prematurely born infants. The auditory-visual enhancement test as used here may have a number of further uses and applications in the clinic and laboratory.     

Signal pulse-rate and judged duration.

Therories which construct perception of time from content of input predict monotonic functions of rate-judged duration of stimuli, and do not account for intersensory differences. Two experiments required Ss to compare directly the durations of paird lights or sounds pulsed at various rates to produce discriminable beats and flickers (6.0, 10.0, 14.0 Hz), and steady signals. Pulsed lights, not sounds, were judged longer than steady, and this visual effect was identical for all flicker rates. Faster pulsled sounds and lights were judged longer than slower ones for all frequency combinations except for 10.0 to 14.0-Hz comparisons with vision. No monotonic function of ratejudged durations of pulses was obtained; the effect was all-or-none. Although pulse rate did affect judged duration, neither simple functions nor symmetry across senses was found.