Linda Petrosino

Modification of instrumentation for research on lingual vibrotactile sensitivity: Elimination of the tongue clamping procedure

A simplified modification in lingual vibrotactile instrumentation involving elimination of the tongue clamping procedure is presented. Reasons for this modification and the advantages are discussed in terms of facilitating clinical testing.

Changes in Lingual Sensitivity as a Function of Age and Stimulus Exposure Time

Effects of duration of stimulus exposure on lingual vibrotactile thresholds were examined across three groups of 10 subjects each (n = 30). Subjects were grouped according to age (child group, mean age = 10.1 yr.; young adult group, mean age = 21.9 yr.; elderly group, mean age = 76.0 yr.). Lingual vibrotactile threshold measurements were obtained for all subjects under 5 conditions of exposure (1, 2, 3, 4, and 5 sec.). Results showed statistically significant differences in threshold among all three age groups. As age increased, thresholds of lingual sensitivity increased (became poorer). Stimulus duration also created significant differences in threshold for all age groups. As stimulus duration increased, thresholds of lingual sensitivity decreased (became better). The children appeared to be the most stable across conditions whereas the elderly group appeared to be the most affected by stimulus duration.

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.

Lingual Vibrotactile Sensation Magnitudes: Comparison of Suprathreshold Responses for Three Different Age Ranges

Vibrotactile magnitude scaling was performed on three different age groups of six normal subjects each. The psychophysical method of magnitude production was used for the scaling of vibratory stimuli applied to the anterior dorsal surface of the tongue. The older subjects produced shallower upper-slope functions than the younger subjects and also showed greater response variability. Behavioral, anatomical, and physiological factors are discussed.

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.

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.

AUDITORY MASKING EFFECTS ON LINGUAL VIBROTACTILE THRESHOLDS AS A FUNCTION OF AGE

Auditory masking effects on lingual vibrotactile thresholds were examined across three groups of 10 subjects each. The first group included children 13 yr. of age or younger, the second group young college age adults, and the third group elderly individuals 66 yr. of age or older. Lingual vibrotactile thresholds were obtained from each group at a frequency of 250 Hz, under experimental conditions of no-masking, narrow-band masking, and wide-band masking. Results showed statistically significant threshold differences between the elderly group and the other two groups for all three experimental conditions. A difference was also detected between experimental conditions when an over-all statistical analysis was performed, but this difference disappeared under more stringent post hoc examination. Results are discussed with respect to current literature on aging and appropriate simplified procedures are recommended for future lingual vibrotactile threshold testing.

A precision method for lingual vibrotactile threshold measurement

This study was designed to evaluate the possible effect of two different psychophysical techniques on lingual vibrotactile sensory thresholds. Ten subjects were tested using the ascending psychophysical method of limits and the forced-choice signal detection technique of threshold assessment. Results indicated that both techniques provided consistent, reliable threshold data, but the forced-choice method yielded lower (more sensitive) lingual sensory thresholds. Results are discussed with respect to the appropriate utilization of both testing procedures.

Intensity difference limens for lingual vibrotactile stimuli

Lingual differential sensitivity for intensity was measured by determining difference limens (DLs) at three different frequencies and five sensation levels. DLs were obtained from five normal adult subjects. The results indicated a relationship between the DL values (expressed as a Weber fraction: AI/I) and frequency. Overall, the data obtained indicate that the lingual sensory system can provide DL functions that are compatible with those of other tactile sensory systems, as well as those derived from other sensory modalities, such as audition.

Threshold influence on vibrotactile magnitude production scaling

The present investigation attempted to look at possible influences that the obtainment of vibrotactile threshold might have on the power function exponent derived from magnitude production scaling. Two groups of six subjects each provided vibrotactile magnitude functions for the lingual dorsum and thenar eminence of the right hand. Group 1 was required to provide a series of vibrotactile thresholds on the test structures prior to scaling. Group 2 performed the scaling task only. Results showed that the inclusion of the threshold task within the test paradigm had no influence on the subsequent scaling activity.