Vibrotactile difference thresholds for intensity and the effect of a masking stimulus

Vibrotactile difference thresholds for intensity were measured at several intensity levels of a test stimulus in the absence of a masking vibration and in the presence of three different amplitudes of a masking vibration. The test stimulus was a 160-Hz vibration delivered to the right index finger. The masking stimulus was a 160-Hz vibration delivered to the right little finger. For the same amplitudes of the test stimulus, △I varied as a direct function of the amplitude of the masking vibration. The smallest △Is resulted from measurements made in the absence of the masking stimulus. The Weber fraction, △I/I, was constant only for the more intense test stimuli in the absence of any masking stimuli. Independent of the presence or level of the masker, the Weber fraction for all stimuli approached approximately the same value, .25, when the test stimuli were raised to 20-dB sensation level. A model is proposed to account for the increase in the Weber fraction as a function of masker intensity and to predict masked thresholds.     

Comparison of child and adult vibrotactile thresholds as a function of frequency and duration

Psychophysical thresholds for the detection of sinusoidal vibration of the thenar eminence of the hand were determined for children and adults. The subjects in the child group were between 8 and 11 years old, and the adults were between 20 and 39 years old. Measurements were made for vibration frequencies ranging from 18 to 700 Hz and stimulus durations ranging from 28 to 1,000 msec. For both children and adults, thresholds were a Il-shaped function of stimulus frequency. However, the exact form of the function was influenced by the age of the subjects. At frequencies above 200 Hz, thresholds were virtually identical for children and adults, but below this frequency children were more sensitive than adults. This finding, in combination with known changes in the anatomy of the Pacinian corpuscle with age, is in agreement with a filter model of this cutaneous receptor. Furthermore, variation of stimulus duration resulted in data in agreement with the theory that two classes of mechanoreceptors, Pacinian and non-Pacinian, mediate the perception of vibration.     

Auditory threshold,signal-to-noise ratio and signal detection theory

The use of Signal Detection Theory has demonstrated that there is not an auditory threshold at the level supposed by classical psychophysics, but has not disproved the existence of an auditory threshold at a lower level. Following the recommended signal detection theory procedure fairly closely, an experiment obtained evidence either of the existence of a signal-to-noise ratio audi tory threshold, or a nonlinear relationship between stimulus and response which could not be statistically distiguished from such a threshold , Using the same apparatus and subjects, audi tory thresholds were also obtained using the classical method of limits. The acoustic pressure for the classical thresholds was about five times as great as for the signal detection theory method.     

Effect of simultaneous auditory stimulation on vibrotactile thresholds

Vibrotactile thresholds were determined at 250 and 400 Hz in the presence of (1) the sounds emitted by the vibrator, (2) continuous tonal or narrow-band masking noise, or (3) a pulsed tone synchronized with the vibrator signal. The measure of a cross-modality effect was the threshold shift occurring between each condition and the control condition, in which earmuff silencers eliminated the vibrator sounds. Continuous tones or noise had no effect upon vibrotactile thresholds. However, auditory signals synchronized with the vibrator signals did significantly elevate vibrotactile thresholds.     

Electrocutaneous stimulation: Psychometric functions and temporal integration

Psychometric functions and psychophysical strength-duration curves were obtained with rectangular electro-cutaneous pulses. The slopes of the psychometric functions were much steeper than corresponding functions in other modalities, with the standard deviation of the distribution only about 0.08 times the threshold. Precise monitoring of stimulus current showed that physiological rather than physical variability was involved. Psychophysical strength-duration curves support the contention that large A-fibers are directly stimulated. Data from this study. as well as from comparable I × t experiments in other senses, are well-fit throughout the range of durations by rectangular hyperbolas. The period over which complete temporal summation occurs is only about 0.5 msec.     

Frequency selectivity using tonal-temporal masking: Diotic vs. dichotic masking

A combined forward-backward masking procedure was used to investigate the threshold of a 30-msec, 500-Hz signal as a function of masker frequency. The signal thresholds were obtained in two signal conditions, diotic (So) and dichotic (S_π), and for two different temporal separations of the maskers. The maskers were 500 msec in duration and were presented at 75 dB SPL. The function relating masked signal threshold to masker frequency was used to describe frequency selectivity in the four conditions. There were no differences in frequency selectivity measured between the diotic and dichotic signal conditions and only a small difference measured between the two intermasker interval conditions. The S_π conditions yielded lower thresholds than did the So conditions. The change in intermasker interval from 10 to 50 msec lowered the threshold maximally 18 dB for the So condition and 13 dB for the S_π condition. The results indicate that in this tonal temporal masking procedure there are no differences between the diotic and dichotic critical bands.     

The effect of skin temperature on vibrotactile sensitivity

The effect of skin temperature on detection of vibrotactile stimuli was measured for vibrations of 30 and 250 Hz. Data for the 250-Hz stimulus supported the results of Weitz (1941), who found that thresholds for 100-, 256-, and 900-Hz vibration varied as a If-shape function of skin temperature with a minimum at about 37°C. Temperature had a negligible effect on sensitivity at 30 Hz. A second experiment examined a range of frequencies between 30 and 250 Hz. Cooling greatly lowered sensitivity only to 150- and 250-Hz stimuli. Warming reduced sensitivity less, but more uniformly across frequencies. It was concluded that cooling may affect vibrotactile thresholds by decreasing the sensitivity of Pacinian corpuscles; the reason for the decrease in sensitivity due to warming is unclear.     

Effects of rate of signal rise and decay on reaction time to the onset and offset of acoustic stimuli

This study assessed the effects of variations in signal rise-decay time on response latencies to the onset and cessation of a 1,000-Hz tone. Onset and offset reactions were combined factorially with five rates of signal rise-decay (0.5, 5, 25, 100, and 250 msec) to produce a total of 10 experimental conditions. Offset RTs were significantly longer than onset RTs when the rise-decay time of the tone was 250 msec. Disparities in speed of reaction to tone onset and cessation were negligible at the remaining rates of signal rise-decay.     

Threshold recognition of phantom-contour objects requires constant contrast velocity

Recognition of phantom objects--those with contours defined by rapid contrast reversal of adjacent fields of dark and light random dots--was investigated under conditions of abrupt or ramped onset and offset. Discrimination contrast thresholds were determined for a random-dot phantom letter in four possible orientations. For abrupt onset or offset, thresholds were almost independent of the duration of presentation time, over a range that varied tenfold, from 34-340 msec. However, when the onset and offset were shaped by a triangular envelope, thresholds were raised, so that form blindness occurred even when peak d ot contrasts exceeded 60%. Also under ramped onset and offset conditions, threshold contrast varied strictly linearly with stimulus duration in all subjects, suggesting a new construct--contrast velocity, the rate of change of contrast critical for phantom-object recognition.     

Men's and women's evaluations of menstrual-related excuses

Based on an attributional analysis of menstrual distress, the present study examined how a woman is evaluated when she attributes an instance of negative social behavior to the approach or onset of menstruation. College men and women were asked to imagine an interaction in which a woman behaves very irritably and then gives one of several excuses for her negative behavior, two of which were menstrual related. Subjects evaluated each excuse in terms of (1) degree of annoyance, (2) blameworthiness, and (3) internality versus externality. The results showed consistent relationships between these evaluations and both sex of subject and general attitudes about menstruation. Males tended to see menstrual-related excuses as less blameworthy and more external than did females. In addition, general attitudes regarding the debilitating effects of menstruation predicted greater tolerance toward the use of menstrual excuses. These results are discussed in terms of their implications for the socialization and continuing reinforcement of menstrual distress.The research reported in this article was supported by grants SOC-7602137 and SOC-7602179 from the National Science Foundation. The authors wish to thank Russ Fazio for his help in collecting the data and Al Rogers and Terry Balaban for their help in analyzing the data. Diane N. Ruble is now at New York University. Ann K. Boggiano is now at the University of Colorado.     

Determinants of tonic and phasic reactions in transswitching

Forty-eight college students were assigned randomly to four groups in a 2 × 2 factorial arrangement of phasic conditional stimuli (samevs. different) and tonic conditional stimuli (samevs. different) to receive 2 days of classical conditioning with a transswitching procedure. Tonic stimuli were a 5-minute projected white triangle or circle; phasic stimuli were a 5-second red or green square superimposed over the tonic stimuli. There were six tonic stimulus segments each day, separated by 20-second periods of no stimulus, three containing six trials of the phasic stimulus paired with shock and three containing six trials of the phasic stimulus alone, in the counterbalanced order. Tonic responding at the onset of the tonic stimuli or during brief periods following its onset were recorded, along with phasic responses to the phasic stimuli. Responses included magnitude of skin conductance responses, frequency of unelicited skin conductance responses, and tonic heart rate. Both skin conductance measures of responding to the tonic stimuli differentiated significantly between positive and negative tonic segments during Day 2, but only in the group with two different tonic stimuli and one phasic stimulus (“standard” transswitching). This supported the hypothesis that tonic stimulus differentiation would be absent when two different phasic stimuli were present. The heart rate data did not support this hypothesis, showing tonic differentiation in both groups with two tonic stimuli. Phasic differentiation controlled by the different phasic stimuli was observed on Day 1; on Day 2, phasic differentiation was present only in the group with two tonic and one phasic stimuli and the group with one tonic and two phasic stimuli. The results were interpreted to mean that temporal contiguity between the tonic stimuli and shock or no shock is not sufficient to establish tonic response differentiation in transswitching.     

Separate "what" and "where" decision mechanisms in processing a dichotic tonal sequence.

Right-handed subjects were presented with a dichotic tonal sequence, whose basic pattern consisted of three 800-Hz tones followed by two 400-Hz tones on the channel and simultaneously three 400-Hz tones followed by two 800-Hz tones on the other. All tones were 250 msec in duration and separated by 250-msec pauses. On any given stimulus presentation, most subjects reported the sequence of pitches delivered to one ear and ignored the other. They further tended significantly to report the sequence delivered to the right ear rather than to the left. However, each tone appeared to be localized in the ear receiving the higher frequency, regardless of which ear was followed for pitch and regardless of whether the higher or lower frequency was in fact perceived.     

NOTE ON SIMULTANEOUS DISCRIMINATION OF VISUAL ATTRIBUTES

van der H eijden A. H. C. Note on simultaneous discrimination of visual attributes. Scand. J. Psychol ., 1972, 13 , 71–72.—A tachistoscopically presented stimulus, provided it is above threshold, results in a visual image with a minimum duration of about 250 msec. In experiments on visual information processing, therefore, the results must be interpreted in terms of 'effective stimulus duration' (exposure time and duration of visual image) rather than exposure time alone.     

Stimulus control of heart rate by auditory frequency and auditory pattern in pigeons

A new method was used to investigate auditory discrimination in pigeons. Basically, the method involves the repeated presentation of one stimulus preceding the single presentation of a different stimulus that is followed by shock. Stimulus control is assessed by the increase in heart rate that accompanies the presentation of the second stimulus. In Experiment 1, the efficiency of the method was explored by determining the frequency difference thresholds of pigeons at 500, 1000, 2000, and 4000 Hz. Weber fractions comparable to those reported in an earlier study using the conditioned suppression method were obtained. Experiment 2 demonstrated that, contrary to results of earlier studies, auditory temporal patterns can exercise differential stimulus control in pigeons. One stimulus consisted of the presentation (once per second) of a 1000-Hz pure tone of 150 msec duration followed by a 2000-Hz pure tone of equal duration; the other was the same except for the reversed order of the frequency components. Results indicated that the frequency pattern and not the loudness pattern of the stimuli was the cue controlling heart-rate changes.     

Emancipatory Research: Then and Now

This discussion piece reflects on menstrual cycle research since the founding of the Society for Menstrual Cycle Research in the context of contemporary research presented in this special issue of Sex Roles. Although women researchers in the 19th century began documenting that normal menstruation is neither disabling nor dangerous, taboos, concealment and avoidance of menstruation persist. Feminist researchers have worked to find ways to support women’s health and wellbeing within a sociocultural milieu still reflecting largely negative views of menstrual cycle phenomena. The present collection of current menstrual cycle research offers useful contextual approaches to understanding why menstruation remains in the shadows, and how to resist negative characterizations, as well as encourage curiosity and body awareness. Alternatives to mainstream corporate and medical views of menstrual phenomena are discussed. Fruitful theoretical and methodological directions for research are identified to support advocacy, educational, and therapeutic interventions for menstrual health.     

The role of tone duration in dichotic temporal order judgment

Over the past two decades, a number of studies have been based on the dichotic temporal order judgment (TOJ) paradigm, to compare auditory temporal processing in various subpopulations to that of young, normal controls. The reported estimates of dichotic TOJ thresholds, expressed as the interstimulus intervals (ISIs) for 75 % accuracy among the controls, have varied. In the present study, we examined the influence of tone duration, within the 10- to 40-msec range, on dichotic TOJ accuracy and threshold. The results indicated that increases in either ISI or tone duration increased dichotic TOJ accuracy similarly, implying that changes in tone duration may affect dichotic TOJs simply by adding to the delay between onset of the tone at the lead ear and onset of the tone at the lag ear. The dichotic TOJ thresholds from three published studies that had used tones as stimuli and the dichotic thresholds from the present study all fell within 0.5 standard deviations from the theoretical line of a 10-msec reduction in threshold for every 10-msec increase in tone duration. When the dichotic TOJ threshold data from the present study and from the published studies were converted to stimulus onset asynchronies (SOAs) and plotted as a function of tone duration, they fell very close to or on a zero-slope line, indicating that when ISI and duration are summed to yield an SOA, dichotic TOJ thresholds are invariant to tone duration within the range of 10–40 msec.     

A sequential theory of psychological discrimination

A theory of discrimination which assumes that subjects compare psychological values evoked by a stimulus to a subjective referent is proposed. Momentary differences between psychological values for the stimulus and the referent are accumulated over time until one or the other of two response thresholds is first exceeded. The theory is analyzed as a random walk bounded between two absorbing barriers. A general solution to response conditioned expected response times is computed and the important role played by the moment generating function (mgf) for increments to the random walk is examined. From considerations of the mgf it is shown that unlike other random walk models [Stone, 1960; Laming, 1968] the present theory does not imply that response conditioned mean correct and error times must be equal. For two fixed stimuli and a fixed referent it is shown that by controlling values of response thresholds, subjects can produce Receiver Operating Characteristics similar or identical to those predicted by Signal Detection Theory, High Threshold Theory, or Low Threshold Theory.     

Auditory sensitivity and tone-sequence reproduction in oral contraceptive users and nonusers

In two stages spanning a single academic year, 10 women using oral contraceptives and 11 not using oral contraceptives were tested on their auditory threshold sensitivity to six frequencies (250, 750, 1500, 3000, 6000, and 8000 Hz) as a function of phases of the menstrual cycle. 11 women (5 users and 6 nonusers) were also tested on their ability to reproduce successively longer tone sequences. Results showed that there was little variation due to phase of the menstrual cycle, with the exception that oral contraceptive users showed lower relative thresholds at low frequencies during the postmenstrual phase. Over-all, oral contraceptive users had higher absolute and relative thresholds than nonusers, except at 3000 Hz. Although not statistically significant, results on the tone-reproduction test showed an enhanced ability to reproduce tones during the premenstrual phase for women using oral contraceptives. Results are discussed in relation to previous findings.     

A Method for the Study of Personality Reactions in Preschool age Children by Means of Analysis of their Play

This investigation studied variability in visual thresholds for six subjects for 50 consecutive days. The results show the following:

1. Session-to-session variability agrees closely with the variability estimates made by Hecht and Zegers.

2. No periodic or cyclic trends appeared for the group or for any individual subject.

3. For all six subjects for the first 15 days of testing, a learning phenomenon was observed for the mean and standard-deviation data. There was a slow rise over the last 10 days of testing for the mean, but not for the standard-deviation data. (A discussion of the possible causes of the rise of the mean over the last 10 days suggested the influence of extraneous factors, such as boredom and fatigue.)

4. No effect of the menstrual cycle upon the threshold values was found.

4. No effect of the menstrual cycle upon the threshold values was found.     

A tactile metacontrast effect

Vibrotactile patterns, generated on the 6×24 array of the Optacon, were presented to subjects’ left index fingertips. The subjects identified these patterns in the absence of any masking stimuli and in the presence of spatially adjacent masking stimuli. The amount of interference in recognizing the patterns was measured as a function of the interval between target and masker onsets. Masking functions similar to those reported in visual metacontrast studies were found; that is, more masking occurred when masker onset followed target onset by 25 to 50 msec than when onsets were simultaneous. Subjects showed more metacontrast when masker energy was reduced, a finding paralleled in the visual literature. The relevance of some models of visual metacontrast to the tactile findings is discussed.