Daniel Harris

Effects of single-session repetitive judgments on magnitude estimation scales for lingual vibrotactile sensation

The human tongue, because it is mucosal in nature and housed within the oral cavity, presents a unique set of problems for suprathreshold vibrotactile magnitude scaling. It was hypothesized that the ideal response mode when testing the lingual structure would entail a single set of stimulus-level judgments to be made by a subject so that fatigue effects and overall subject discomfort associated with lingual vibrotactile suprathreshold testing could be reduced. The purpose of the present investigation was to study the possible effects that single-session repetitive judgments would have on lingual vibrotactile magnitude estimation outcome. Twenty subjects (M age = 23.25 years) participated in a single-session magnitude estimation paradigm which required them to make three magnitude estimation judgments at each of nine stimulus intensity levels. The three data runs were statistically analyzed using a multivariate mixed-model analysis of variance. There appeared to be no statistical differences between the three magnitude scaling runs at any of the nine sensation levels, whether they were compared separately or in all possible combinations, when alpha was set at .05. The results are discussed as being supportive of the possibility that a single set of response judgments can be employed in lingual vibrotactile magnitude scaling. Factors associated with the single-response set, such as ability to run more subjects in less time, better assurance of open-ended responses from subjects, and the increased likelihood of subject response spontaneity are also discussed.

THE EFFECT OF PREFERENCE FOR ROCK MUSIC ON MAGNITUDE-ESTIMATION SCALING BEHAVIOR IN YOUNG ADULTS

The purpose of the present study was to examine the effect of preference for rock music on magnitude-estimation scaling behavior in young adults. Two groups of young adults, 20 who liked rock music and 20 who did not like rock music, were tested. Subjects were instructed to assign numerical values to a random series of nine suprathreshold intensity levels of a 10-second sample of rock music. Analysis indicated that there was a difference in performance by the two groups of subjects on the magnitude-estimation scaling task. The subjects who liked rock music provided significantly lower mean numerical responses than the subjects who did not like rock music for all nine suprathreshold intensities.

Sensation magnitude scales for vibrotactile stimulation of the tongue and thenar eminence.

This study represents the first attempt to generate magnitude-estimation and magnitude-balance functions for the human tongue. Vibrotactile magnitude scales for the tongue and thenar eminence of the hand were investigated for nine adult subjects. The methods of magnitude estimation and magnitude production were used to obtain magnitude-balance functions for both structures. The magnitude-estimation task resulted in magnitude functions for the tongue which were similar in slope value to those found for the thenar eminence. The magnitude-production task also gave magnitude functions which were similar in slope value for the two structures.

Instrumentation for magnitude estimation and cross‐modality matching of auditory and lingual vibrotactile sensations

An instrumentation system has been designed to investigate the relationship between auditory and oral tactile sensory processes. This instrumentation can be employed to obtain judgments of auditory and oral tactile sensation magnitudes by the psychophysical scaling methods of magnitude estimation and cross‐modality matching. The stimulus generating units, stimulus measurement units, and psychophysical sensation magnitude scaling procedures are described. Previous research on the relationship of auditory and oral tactile sensory processes has frequently involved disruption of one or both sensory modes. The instrumentation system described permits investigation of these sensory channels in a nondisruptive manner. The results of two preliminary studies employing the described instrumentation and experimental techniques indicate that the system provides a viable means for investigating auditory and oral tactile sensory interactions in normal and speech‐disordered subjects.

Lingual vibrotactile threshold shift during magnitude-estimation scaling: Effects on magnitude-estimation responses and scaling behavior

The purpose of the present study was to determine if lingual vibrotactile threshold shifts occurred during magnitude-estimation scaling of suprathreshold stimuli presented to the dorsal surface of the tongue. Possible relationships of the lingual vibrotactile threshold shifts to suprathreshold stimulus intensity, magnitude-estimation responses, and overall scaling behavior were explored. A single group of 24 subjects with an age range of 18 to 22 years participated in this study. Each subject performed two magnitude-estimation tasks. In one of the tasks, threshold of sensitivity was determined after every suprathreshold numerical response of the subject. If a threshold shift was recorded, threshold was allowed to return to the pretest baseline level before continuing to the next suprathreshold stimulus presentation. The results showed that threshold shift did occur during lingual vibrotactile magnitude-estimation scaling, and that it was related to suprathreshold stimulus intensity. The results also showed that the numerical magnitude-estimation responses of the subjects were different for the two scaling tasks. Overall scaling behavior of the subjects in the form of power-function exponents was not different for the two tasks.

The effect of contactor area on vibrotactile magnitude function exponents for the tongue and hand

The method of magnitude production was used to investigate subjective vibratory magnitude functions for the hand and tongue. Three different contactor areas were employed. The subjects were 10 normal young adults. The results indicated that magnitude slope functions were inversely related to contactor area for both structures tested. The results suggest that the number of sensory units activated by a stimulus may be an important variable in establishing vibratory sensation magnitude functions.

Effects of aging on responses to suprathreshold lingual vibrotactile stimulation.

Lingual vibrotactile suprathreshold sensation magnitudes were investigated across four age groups (M ages = 7.8 yr., 193 yr., 45.2 yr., and 57.0 yr, age range = 5 to 64 yr.) by employing the psychophysical methods of magnitude estimation and cross-modal matching. Lingual vibrotactile stimuli were presented in combination with auditory stimuli for the cross-modal matching task. For lingual vibrotactile magnitude estimation, both the upper and lower power functions were steeper for the oldest age group. The power functions for cross-modal matching in which the vibratory stimulus was the standard showed asymptotic growth at about 25-dB sensation level for the three older age groups, but not for the youngest age group. Straight-line power functions were obtained for all age groups on the cross-modal matching task when the auditory stimulus was the standard, with the older aged subjects making larger lingual vibrotactile magnitude adjustments to the lower level auditory stimuli than the younger aged subjects. These results are discussed in relation to neurophysiological and behavioral changes which occur during development and aging.

Stability of magnitude-production scales for lingual vibrotactile sensation.

The stability of lingual vibrotactile magnitude scales produced by the method of magnitude production was investigated for 10 adult subjects. These subjects produced highly stable magnitude scales across two test sessions separated by 1 wk. The subjects appeared to use absolute rather than ratio scales in the magnitude-production task. A discussion of the stability of the scales is conducted with reference to the likelihood of an internal, absolute mechanism for magnitude scaling.

Magnitude Estimation and Magnitude Production: Stimulus Frequency Effects on Magnitudes of Lingual Vibrotactile Sensation

The methods of magnitude estimation and magnitude production were employed to investigate the effects of stimulus frequency on suprathreshold lingual-vibrotactile sensation-magnitude functions. The method of magnitude estimation was used to obtain numerical judgments of sensation magnitudes for nine stimulus intensities presented to the anterior dorsum of the tongue. The vibrotactile stimulus frequencies employed for 10 subjects (M age = 21.1 yr.) were 100, 250, and 400 Hz. The numerical responses obtained during the magnitude-estimation task were in turn used as stimuli to obtain magnitude-production values for the same three vibrotactile stimulus frequencies. The results appeared to present two suggestions. First, the effects of stimulus frequency on lingual vibrotactile-sensation magnitudes may be dependent on the psychophysical method used in any particular experiment. Second, lingual-vibrotactile magnitude-estimation scales may demonstrate asymptotic growth functions above about 25 dB sensation level. The limitation in the growth of sensation magnitude occurred for all three vibrotactile stimulus frequencies employed.

Lingual vibrotactile/auditory magnitude estimation and cross-modal matching: comparison of suprathreshold responses in men and women.

The purpose of this study was to investigate the response patterns of men and women to suprathreshold lingual-vibrotactile and auditory stimulation. The psychophysical methods of magnitude estimation and cross-modal matching were used on a group of 10 men (M age = 19.6 yr.) and 10 women (M age = 20.2 yr.). Analysis showed that the men and women performed differently on the magnitude-estimation tasks and similarly on the cross-modal matching tasks. These results suggested that sex differences on suprathreshold psychophysical scaling may be related to the way men and women use numbers as opposed to possible differences in the perception of suprathreshold sensory stimuli by men and women.