Perception Of Temporal Order Research Articles

Auditory Pattern Discrimination in the Absence of Spectral Cues

Previous research has shown that brief sounds can be discriminated on the basis of differences in the spectral content of the waveform. The aim of the present work was to assess the importance of spectral processing in the perception of temporal order. In the first study, in an effort to prevent spectral information from serving as the basis for perception of temporal order, sequences of four tones were presented dichotically in a repeated tape loop. Component tones in the sequence were administered to the left or right ear according to a predetermined random order. On each trial, two sequences of tones were presented, and the task of the observer was to determine whether the order of presentation was the same or different for the two sequences. The duration of component sounds required for reliable discrimination was 90 msec. The duration threshold for a diotic presentation was 10 msec. A second study investigated the perception of temporal order for high and low tone bursts presented in a nonrepeated sequence consisting of the two tones, a noise, and a buzz. Here the task was to determine whether the order of the high and low tones in the two sequences was the same or different. The location and temporal order of the buzz and noise in the two sequences were randomized and irrelevant to the discrimination. Temporal order could be perceived when the duration of each component sound was 20 msec. [This research was supported by the National Institute of Health.]

Perception of Temporal Order: Special Rules for the Initial and Terminal Sounds of Sequences

If a pattern of three or four successive sounds (consisting of hisses, tones, and buzzes) is repeated without pause, listeners cannot identify the order at durations of individual items well above 100 msec, even though each of the component sounds is heard clearly. However, if two of these sounds are each presented once with one following the other, it is possible to identify temporal order for durations below 50 msec. It has been suggested that accurate perception of order with such stimulus pairs might involve special mechanisms permitting identification of items at the beginning and end of auditory sequences [Warren, Obusek, Farmer, and Warren, “Auditory Sequence: Confusion of Patterns other than Speech and Music,” Science 164, 586 (1969)]. The present experiments demonstrate that introduction of a silent interval of 3 sec between repetitions of sequences consisting of three or four successive items each lasting 200 msec facilitates detection of temporal order. It appears that sounds present at initiation and termination of a sequence can be identified readily, and that these cues can be separated experimentally from direct identification of temporal succession. [This research was supported by the National Science Foundation.]

Effect of Unilateral Brain Damage on Perception of Temporal Order

The hypothesis that temporal perception is mediated by the dominant (left) hemisphere was tested by presenting sequential audiovisual stimuli to 47 patients suffering from unilateral lesions in the left or right hemisphere and to 42 control patients free from neurological disorders. The patients, presented with sequences of 3, 4 or 5 stimuli (3 colored lights and 2 sounds), chose any stimulus as a starting point, and identified the order of stimuli following it in the continuous sequence by pointing at the stimulus source. The results, analyzed by analysis of variance, showed that performance of patients suffering from left hemispheric lesion was significantly impaired as compared with that of the other patients. The data were interpreted as showing that in parallel with the specialization of the right hemisphere in spatial perception, the left hemisphere specializes in temporal perception.

Monaural temporal interactions.

The monaural temporal interaction of transients was investigated by using a “mirror-image” paradigm. A pair of unequal monaural clicks in which the less intense click precedes the more intense click by a given interpulse interval (backward masking) was discriminated from an identical pair of clicks in which the more intense click precedes the less intense click by the same interval (forward masking). The functions obtained show an initial rise in discrimination as a function of increasing interpulse interval (Δt) followed by a leveling of the curve at a high discrimination level for Δt's of up to approximately 8–10 msec, followed by a decrease in discrimination to approximately 12–15 msec, followed by a second increase in discrimination at Δt's greater than 15 msec. Comparing the discrimination of mirror-image click pairs to forward masking and to backward masking alone indicates that monaural temporal interactions exist at intermediate interpulse intervals even though forward and backward masking are no longer evident. At these intervals, the discrimination is unrelated to the perception of temporal order. The shape of the functions and the Δt range over which it is evident are dependent upon the relative intensities of the two clicks comprising the pair. At longer intervals (greater than 15 msec), perception of temporal order is the dominant cue. Possible mechanisms are discussed.

Temporal Order and Perceptual Classes

Continuing our work on temporal order perception, we have measured the duration of four equal segments in a continuously repeated sequence of four pure tones necessary for correct perception of their temporal order. When all four tones were within a musical fourth (critical band?) the segment duration necessary for correct order perception was 125 msec—the same as we obtained earlier for natural vowels. However, when the tones were more widely spaced in frequency, the duration of each segment necessary for correct order perception was considerably greater (up to 500 msec) depending on the specific distribution of pure tones. Likewise, for a mixture of “different” stimuli (e.g., pure tones, white noise, etc.) segment durations again were considerably greater than 125 msec for correct order perception. It appears from these tests that much of the segment time in excess of 125 msec necessary for correct order perception results from the need to shift attention among “different” classes of stimuli. [Work supported by NIH.]

Auditory Temporal Order Judgments Perturbed by Tactile Stimuli

Hirsh and Sherrick [J. Exp. Psychol. 62, 423–432 (1961)] determined that the limen for perception of temporal order for two stimuli is about the same (ca. 20 msec) for vision, audition, and touch. They suggested that a central processing system must be responsible for the uniformity of results. The present experiments test the hypothesis that the same system processes all modality inputs and that judgments of order in one modality can be perturbed if signals to a second modality are simultaneously present. Observers were presented with successive bursts of noise or tones dichotically, simultaneously with mechanical taps to each index fingertip. When the succession of auditory stimuli was the same as for the tactile, e.g., left-right, detection of order was unperturbed. When the succession for one modality opposed that of the other, e.g., auditory left-right, tactile right-left, detection was seriously degraded. Several parameters of stimuli that diminish or augment these effects have been studied and will be discussed. [Research supported by the National Institutes of Health, Department of Health, Education, and Welfare.]

Effect of Silent Intervals on the Perception of Temporal Order for Vowels

Experiments to determine the duration of four equal vowel segments necessary for correct perception of temporal order in a continuously repeated sequence of four vowel sounds were reported recently [I. B. Thomas et al., “Temporal Order in the Perception of Vowels,” J. Acoust. Soc. Amer. 48 (October 1970)]. In these earlier experiments each of the segments consisted entirely of vowel sound so that there were no silent intervals at all within a loop. In the present experiments, each of the four segments consisted of 50 msec of one of the vowels followed by a silent interval of variable duration. The vowels used were /i/, /ɛ/, /a/, /u/; total segments (vowel+silence) ranged in duration from 300- to 75 msec. Twenty subjects heard all stimuli binaurally in phase through headphones. They were required to state the order in which the vowel sounds occurred. For segment durations (T) of 100 msec or greater, order identification was near perfect; for T=87 msec score was 65%; for T=75 msec score was near chance (16.7%). A comparison of these results with those obtained in the earlier experiment shows that the silent interval facilitates order perception. [Work supported by NIH.]

Temporal-Order Perception of Vowel Sequences with Monaural and Binaural Presentation

The ability of subjects to repeat alternated speech depends on the alternation rate. The possibility that alternation interferes with the perception of temporal order was investigated in an experiment in which subjects determined the temporal order of vowel sequences under monaural and binaural conditions of presentation. Test stimuli were formed from segments of the vowels /i, ɛ, a, u/. Each stimulus consisted of four equal segments of the four vowels arranged in a random order. Segment duration was varied from 300 to 50 msec. For half the stimuli, the vowels were contiguous and presented to one ear, while for the remainder of the stimuli adjacent vowels were presented to opposite ears. On a given trial, using either the monaural mode or the binaural modes, the ability of subjects to determine the vowel order decreased monotonically with segment duration. Performance varied from near perfect with 300 msec segments to near chance with 50 msec segments. Performance with binaural stimuli was consistently lower than with monaural stimuli.

Perception of Temporal Order for Speech Sounds

Following the technique described in the work of R. M. Warren et al. [“Auditory Sequence: Confusion of Patterns Other Than Speech or Music,” Science 164, 586 (1969)] concerning the perception of temporal order in a continuously repeated sequence of four sounds, we investigated the duration of the four (equal) segments necessary for correct perception of the temperal order of four vowel sounds. The vowels chosen were /i/, /ε/, /a/, /u/; all vowel samples were spliced from the enunciations of one speaker (PBH) and were controlled for pitch (125 Hz) and true rms intensity. The duration of each vowel segment, T, was varied from 75 to 300 msec; vowel order was randomized for each value of T. In identifying temporal order, listeners achieved near perfect scores (>90%) for T⩾125 msec; for T⩽100 msec, scores were near chance (16.7%). The marked difference between the segment durations (T) necessary for correct perception of temporal order for vowels (T≈100 msec) and nonspeech sounds (T from 300 to 700 msec) suggests that this technique can provide a sensitive measure of the “speechlikeness” of synthetic stimuli. [Work supported by NIH.]

Temporal Ordering of Events in Haptic Space

The most rapid acquisition of skill in the use of complex vibrotactile displays will occur when the capabilities of the organism are most efficiently exploited by the display code. When spatiotemporal patterns are chosen as the coding scheme, the problem of perception of temporal order is of great importance. The present paper describes the effects on the limen for order of two events, of the quality of the stimuli, their spacing on the body, and their intensive relations. The results suggest the presence of limiting conditions for the spatial and, by analogy, the temporal density of vibrotactile patterns. Comparisons are made with results reported previously, and a hypothesis is developed concerning the onset and timing of stimuli in relation to the capacity of the nervous system to augment the clarity of sensory events and to transfer the argumentation to successive locations on the sensory surface.

Auditory temporal masking and the perception of order.

An investigation of the effects of frequency, intensity, and time on the perception of temporal order and the amount of temporal masking produced under conditions of a short burst (12 msec) of tone separated temporally from a narrow-band noise indicates a similarity of function underlying the two phenomena. Temporal masking is greater and the perception of temporal order is more difficult when the signal is centered in the band of noise. Temporal masking is greater and the perception of temporal order is more difficult for a weak signal than for a more intense signal. The observed temporal masking can be interpreted in terms of a cochlear model. The relationship between temporal masking and the perception of temporal order is discussed in terms of a hierarchy of level of perception brought about by temporal cues.

Backward Masking and the Perception of Temporal Order

Four subjects were run in a backward-masking task in which the dependent variable was the duration of the silent interval between the signal and the noise. Three frequencies, 850, 1500, and 2600 Hz were employed as signals at sensation levels of 12, 24, and 36 dB. A narrow band of frequencies centered at 1500 Hz and presented at 70 dB SPL was employed as the noise. The method of limits was used to determine threshold values. Subsequently, seven subjects were run in a similar task but instructed to report the temporal order of the signal and the noise. The same frequencies and noise band reported above were employed. The method of constant stimuli was used to determine threshold values. Results of the study showed that the frequency centered in the band demonstrated the largest threshold values both in backward masking and in the perception of temporal order. The low-frequency signal demonstrated the smallest thresholds of backward masking and the perception of temporal order. The function relating intensity of the masked signal and threshold was similar for the backward masking and the perception of order. The threshold for perception of temporal order was, however, approximately 10 msec greater than that for backward masking. [This study was supported by grant frown NSF.]

Intermodal perception of temporal order and motor skills: effects of age.

Employing visual, auditory, and tactile stimuli, intermodal differences in perceptual latency were inferred by means of perception of temporal order (PTO) and by varieties of serial reaction times (RT) to the same stimuli. Skill at reading, peg board, tapping, and tracking was also determined for the same Ss. Mean intermodal differences in latency inferred from PTO were significantly different from those obtained from mean RTs. A correlation matrix showed that individual differences in visual, auditory and tactile latencies inferred from PTO were relatively independent of latencies inferred from RT. Consonant with previous studies, PTO scores correlated with reading rate and also with peg board speed. Taking age of Ss into account, the latter correlations were seen to be due exclusively to the presence of older Ss, who did show a correlation between PTO and RT. It was hypothesized that aged Ss show a decrease in perceptual “channel capacity” and a resulting overloading of short-term memory when faced with a complex perceptual and motor task.

Perception of temporal order and relative visual latency.

Judgments of temporal order to monocular pairs of flashes of equal luminance delivered at various onset asynchronies to the light-adapted fovea and periphery show that uncertainty of temporal order results when the onset of the foveal flash is delayed. Relative latencies vary as a function of peripheral (nasal vs. temporal) locus stimulated.

PERCEPTION OF TEMPORAL ORDER OF STIMULI DIFFERING IN SENSE MODE AND SIMPLE REACTION TIME.

Judgments of temporal order (method of constant stimuli) were obtained as a function of the delay between the onset of a visual and an auditory stimulus. Simple reaction times were also obtained to both the visual and the auditory stimulus. Differences in reaction time could not be used to predict the stimulus asynchrony for temporal order judgments, because the onset of the auditory stimulus had to precede the onset of the visual stimulus for 50% judgment of “click first,” whereas the auditory reaction time was significantly shorter than the visual reaction time. A speculative explanation is offered to account for the differences between the present findings and those of Hirsh and Sherrick (1961).

Perception of Temporal Order and Loudness Judgments for Dichotic Clicks

The effect of a loudness cue on the perception of the temporal order of dichotically presented clicks was investigated. It was shown that one can find a range of temporal intervals between dichotically presented clicks for which increasing temporal separation results in a decrease in the correct judgment of temporal order.

“The Effect of Handedness on the Perception of Simultaneity and Temporal Order”

“The Effect of Handedness on the Perception of Simultaneity and Temporal Order”

Auditory Perception of Temporal Order

Auditory Perception of Temporal Order

Auditory Perception of Temporal Order

Whereas temporal intervals as short as a few milliseconds are sufficient to separate two brief sounds so that a listener will report that there are two (instead of only one) sounds, a longer separation time of between 15 and 20 msec is required for the listener to report correctly which of the two sounds preceded the other. This minimum temporal interval appears to be independent of the kinds of sounds used: whether short or long, of high or low frequency, of narrow or wide band width. There is some suggestion that rise-time and duration may change this minimum interval, but these somewhat secondary relations are not investigated in detail here. The length of the required temporal interval suggests that the judgment of order requires other mechanisms than those associated with the peripheral auditory system.