Infants’ and adults’ use of duration and intensity cues in the segmentation of tone patterns

Adults and 8-month-olds were presented with sequences in which every third complex tone was either longer or more intense. Segmentation was measured by comparing the detection of silent gaps inserted into three possible locations in each pattern: Silent gaps inserted at perceived segmentation boundaries are harder to detect than gaps within perceived phrases or groups. A go/no-go conditioned head-turn (hand-raising for adults) procedure was used. In Experiment 1, detection was worse for the gaps following the longer complex tones than for the gaps at the other locations, suggesting that the longer tones marked the ends of perceived groups for both infants and adults. Experiment 2 showed that an increase in intensity did not result in any systematic grouping at either age.     

Internal clock processes and the filled-duration illusion

In 3 experiments, the authors compared duration judgments of filled stimuli (tones) with unfilled ones (intervals defined by clicks or gaps in tones). Temporal generalization procedures (Experiment 1) and verbal estimation procedures (Experiments 2 and 3) all showed that subjective durations of the tones were considerably longer than those of unfilled intervals defined either by clicks or gaps, with the unfilled intervals being judged as approximately 55%-65% of the duration of the filled ones when real duration was the same. Analyses derived from the pacemaker-switch-accumulator clock model incorporated into scalar timing theory suggested that the filled/unfilled difference in mean estimates was due to higher pacemaker speed in the former case, although conclusively ruling out alternative interpretations in terms of attention remains difficult.     

Objects and events in the attentional blink

When two visual targets, T1 and T2, are presented in rapid succession, detection or identification of T2 is almost universally degraded by the requirement to attend to T1 (the attentional blink, or AB). One interesting exception occurs when T1 is a brief gap in a continuous letter stream and the task is to discriminate its duration. One hypothesized explanation for this exception is that an AB is triggered only by attention to a patterned object. The results reported here eliminate this hypothesis. Duration judgments produced no AB whether the judged duration concerned a short gap in the letter stream (Experiment 1) or a letter presented for slightly longer than others (Experiment 2). When identification of an identical longer letter T1 was required (Experiment 3), rather than a duration judgment, the AB was reestablished. Direct perceptual judgments of letter streams with gaps embedded showed that whereas brief gaps result in the percept of a single, briefly hesitating stream, longer gaps result in the percept of two separate streams with a separating pause. Correspondingly, an AB was produced in Experiment 4, when participants were required to judge the duration of longer T1 gaps. We propose that, like spatially separated objects, temporal events are parsed into discrete, hierarchically organized events. An AB is triggered only when a new attended event is defined, either when a long pause creates a new perceived stream (Experiment 4) or when attention shifts from the stream to the letter level (Experiment 3).     

Effects of pitch distance and likelihood on the perceived duration of deviant auditory events

When a deviant (oddball) stimulus is presented within a series of otherwise identical (standard) stimuli, the duration of the oddball tends to be overestimated. Two experiments investigated factors affecting systematic distortions in the perceived duration of oddball stimuli. Both experiments used an auditory oddball paradigm where oddball tones varied in both their pitch distance from the pitch of a standard tone and their likelihood of occurrence. Experiment 1 revealed that (1) far-pitch oddballs were perceived to be longer than near-pitch oddballs, (2) effects of pitch distance were greater in low-likelihood conditions, and (3) oddballs in later serial positions were perceived to be longer than oddballs in earlier serial positions. The above effects held regardless of whether oddballs were higher or lower in pitch than the standard. Experiment 2 revealed a pattern of response times in an oddball detection task that generally paralleled the pattern of data observed in Experiment 1; across conditions, there was a negative correlation between detection times and perceived duration. Taken together, the results suggest that the observed effects of oddball pitch, likelihood, and position on perceived duration are at least partly driven by how quickly individuals are able to initiate timing the oddball following its onset. Implications for different theoretical accounts of the oddball effect are discussed.     

Effects of aging on absolute identification of duration

Experiments to examine the effects of aging on the ability to identify temporal durations in an absolute identification task are reported. In Experiment 1, older adults were worse than younger adults in identifying a tone's position within a series of 6 tones of varied durations. In Experiment 2, participants were required to identify a tone's position in 9 tones of varied durations. Older adults' performance was again worse than that of younger adults; moreover, they showed a qualitatively different pattern of errors than younger adults. In Experiment 3, in which the tones varied in pitch, the performance of older adults was worse than that of younger adults, but the error patterns of the 2 groups were similar. The results suggest that older adults have distorted memory representations for durations but not for pitch.     

The representation of pitch in auditory imagery: Evidence from S-R compatibility and distance effects

In three experiments we explored the nature of representations constructed during the perception and imagination of pitch. We employed a same–different task to eliminate the influence of nonauditory information and to minimise use of cognitive strategies on auditory imagery. A reference tone of frequency 1000, 1500, or 2000 Hz, or an imagined tone of a pitch indicated by a visual cue, was followed by a comparison tone (1000, 1500, or 2000 Hz) to which either a speeded same or different response was required. In separate experiments, same–different judgements were mapped to vertically (Experiments 1 and 2) and horizontally arranged responses (Experiment 3). Judgements of tones closer in pitch yielded longer reaction times and higher error rates than more distant tones, indicating a pitch distance effect for perceptual and imagery tasks alike. In addition, in the imagery task, same–different responses were faster when low-pitched tones demanded a bottom or left key response and high-pitched tones a top or right response than vice versa, suggesting that pitch is coded spatially. Together, these behavioural effects support the assumption that both perceived and imagined pitch are translated into an analogical representation in the spatial domain.     

Auditory pattern perception: the effect of tone location on the discrimination of tonal sequences.

This study examined the effect of tonal location on the discrimination of sequences differing in the order of the tones and on their perceived grouping. The frequency range between the sequential tones was held constant. When all tones came from the same location, the sequence was rated as integrated, but when the higher frequency tones came from a different location than the lower frequency tones, the sequence was rated as segregated. Listeners discriminated the sequences in a 3IFC task. Discrimination performance was impaired when the sequence was split between two locations and tonal order was changed in only one location, even though the order of tones in different locations was changed. This result suggests that listeners have difficulty relating tones across locations or in different perceptual groups. Performance in this experiment is generally better than that observed by Barsz (1988), and it is suggested that the level of stimulus uncertainty explains this difference.     

Auditory pattern perception: The effect of tone location on the discrimination of tonal sequences

This study examined the effect of tonal location on the discrimination of sequences differing in the order of the tones and on their perceived grouping. The frequency range between the sequential tones was held constant. When all tones came from the same location, the sequence was rated as integrated, but when the higher frequency tones came from a different location than the lower frequency tones, the sequence was rated as segregated. Listeners discriminated the sequences in a 3EFC task. Discrimination performance was impaired when the sequence was split between two locations and tonal order was changed in only one location, even though the order of tones in different locations was changed. This result suggests that listeners have difficulty relating tones across locations or in different perceptual groups. Performance in this experiment is generally better than that observed by Barsz (1988), and it is suggested that the level of stimulus uncertainty explains this difference.     

Perceptual interactions between musical pitch and timbre.

These experiments examined perceptual interactions between musical pitch and timbre. Experiment 1, through the use of the Garner classification tasks, found that pitch and timbre of isolated tones interact. Classification times showed interference from uncorrelated variation in the irrelevant attribute and facilitation from correlated variation; the effects were symmetrical. Experiments 2 and 3 examined how musical pitch and timbre function in longer sequences. In recognition memory tasks, a target tone always appeared in a fixed position in the sequences, and listeners were instructed to attend to either its pitch or its timbre. For successive tones, no interactions between timbre and pitch were found. That is, changing the pitches of context tones did not affect timbre recognition, and vice versa. The tendency to perceive pitch in relation to other context pitches was strong and unaffected by whether timbre was constant or varying. In contrast, the relative perception of timbre was weak and was found only when pitch was constant. These results suggest that timbre is perceived more in absolute than in relative terms. Perceptual implications for creating patterns in music with timbre variations are discussed.     

Temporal summation of 500-Hz tones and octave-band noise bursts in infants and adults

A visually reinforced operant procedure was employed to obtain 2-point threshold-duration functions in 7-month-old infants and adults in two experimental paradigms. In Experiment 1, thresholds were determined for 10- and 100-msec, 500-Hz tones and octave-band noise bursts presented in quiet and noise backgrounds. Threshold-duration functions were significantly steeper for infants than for adults under all experimental conditions, and did not differ in slope as a result of differences in either stimulus bandwidth or masking noise. In Experiment 2, thresholds for trains of brief 500-Hz tone pulses were examined in infant and adult subjects. Infant functions were adult-like for integration of multiple-pulse stimuli, suggesting that the traditional, long-term process of temporal summation is mature by 7 months of age. Differences between the present results and those previously obtained for 4-kHz stimuli appear to be consistent with the view that different mechanisms are involved in the detection of low- and high-frequency signals.     

Name that percussive tune: Associative memory and amplitude envelope†

A series of experiments demonstrated novel effects of amplitude envelope on associative memory, with tones exhibiting naturally decaying amplitude envelopes (e.g., those made by two wine glasses clinking) better associated with target objects than amplitude-invariant tones. In Experiment 1 participants learned associations between household objects and 4-note tone sequences constructed of spectrally matched pure tones with either “flat” or “percussive” amplitude envelopes. Those hearing percussive tones correctly recalled significantly more sequence–object associations. Experiment 2 demonstrated that participants hearing percussive tones learned the associations more quickly. Experiment 3 used “reverse percussive” tones (percussive tones played backwards) to test whether differences in overall energy might account for this effect, finding they did not lead to the same level of performance as percussive tones. Experiment 4 varied the envelope at encoding and retrieval to determine which stage of the task was most affected by the envelope manipulation. Participants hearing percussive tones at both encoding and retrieval performed significantly better than the other three groups (i.e., flat at encoding/percussive at retrieval, etc.). We conclude that amplitude envelope plays an important role in learning and memory, a finding with relevance to psychological research on audition and associative memory, as well as practical relevance for improving human–computer interface design.     

Aging and the Ranschburg effect: no evidence of reduced response suppression in old age

Two experiments tested 1 aspect of L. Hasher and R. T. Zacks's (1988) reduced inhibition hypothesis, namely, that old age impairs the ability to suppress information in working memory that is no longer relevant. In Experiment 1, young and older adults were asked to recall lists of letters in the correct order. Half of the lists contained repeated items while half were control lists. Recall of nonadjacent repeated items was worse than that of control items. This Ramschburg effect was larger (i.e., greater response suppression) in older than in young adults. In Experiment 2, young and older adults were required either to recall the list or to report if there was a repeated item. Repetition detection was high and similar in the 2 age groups. When age differences in overall performance were taken into account, there was evidence of increased repetition inhibition with age in both experiments. Thus, contrary to the general reduced inhibition hypothesis, the specific process of response suppression during serial recall is not reduced by aging.     

Effects of environmental support on overt and covert visuospatial rehearsal

People can rehearse to-be-remembered locations either overtly, using eye movements, or covertly, using only shifts of spatial attention. The present study examined whether the effectiveness of these two strategies depends on environmental support for rehearsal. In Experiment 1, when environmental support (i.e., the array of possible locations) was present and participants could engage in overt rehearsal during retention intervals, longer intervals resulted in larger spans, whereas in Experiment 2, when support was present but participants could only engage in covert rehearsal, longer intervals resulted in smaller spans. When environmental support was absent, however, longer retention intervals resulted in smaller memory spans regardless of which rehearsal strategies were available. In Experiment 3, analyses of participants’ eye movements revealed that the presence of support increased participants’ fixations of to-be-remembered target locations more than fixations of non-targets, and that this was associated with better memory performance. Further, although the total time fixating targets increased, individual target fixations were actually briefer. Taken together, the present findings suggest that in the presence of environmental support, overt rehearsal is more effective than covert rehearsal at maintaining to-be-remembered locations in working memory, and that having more time for overt rehearsal can actually increase visuospatial memory spans.     

Aging and auditory temporal sequencing: ordering the elements of repeating tone patterns

In a series of experiments, we examined age-related differences in adults' ability to order sequences of tones presented at various speeds and in contexts designed to promote or to impede stream segregation. In Experiment 1, 32 listeners (16 young, 16 old) were required to identify two repeating sequences that consisted of four tones (two from a high and two from a low frequency range) in different order. In Experiment 2, 32 listeners were required to judge whether the two recycled patterns from Experiment 1 were the same or different. In Experiment 3, four young and four old listeners were tested on the tasks of Experiment 2 over an extended period. In Experiment 4, 16 young and 16 old listeners were tested with sequences that were not recycled and were composed of tones drawn from a narrow frequency range. Elderly adults were less able than young adults to distinguish between tone sequences with contrasting order, regardless of the speed of presentation, the nature of the task (identification vs. same/different), the amount of practice, the frequency separation of the tones, or the presence or absence of recycling. These findings provide evidence of a temporal sequencing impairment in elderly listeners but reveal no indication of age differences in streaming processes.     

Discrimination of time intervals presented in sequences: spatial effects with multiple auditory sources

This article discusses two experiments on the discrimination of time intervals presented in sequences marked by brief auditory signals. Participants had to indicate whether the last interval in a series of three intervals marked by four auditory signals was shorter or longer than the previous intervals. Three base durations were under investigation: 75, 150, and 225 ms. In Experiment 1, sounds were presented through headphones, from a single-speaker in front of the participants or by four equally spaced speakers. In all three presentation modes, the highest different threshold was obtained in the lower base duration condition (75 ms), thus indicating an impairment of temporal processing when sounds are presented too rapidly. The results also indicate the presence, in each presentation mode, of a 'time-shrinking effect' (i.e., with the last interval being perceived as briefer than the preceding ones) at 75 ms, but not at 225 ms. Lastly, using different sound sources to mark time did not significantly impair discrimination. In Experiment 2, three signals were presented from the same source, and the last signal was presented at one of two locations, either close or far. The perceived duration was not influenced by the location of the fourth signal when the participant knew before each trial where the sounds would be delivered. However, when the participant was uncertain as to its location, more space between markers resulted in longer perceived duration, a finding that applies only at 150 and 225 ms. Moreover, the perceived duration was affected by the direction of the sequences (left-right vs. right-left).     

The effect of intensity on relative pitch

In two experiments, we examined the effect of intensity and intensity change on judgements of pitch differences or interval size. In Experiment 1, 39 musically untrained participants rated the size of the interval spanned by two pitches within individual gliding tones. Tones were presented at high intensity, low intensity, looming intensity (up-ramp), and fading intensity (down-ramp) and glided between two pitches spanning either 6 or 7 semitones (a tritone or a perfect fifth interval). The pitch shift occurred in either ascending or descending directions. Experiment 2 repeated the conditions of Experiment 1 but the shifts in pitch and intensity occurred across two discrete tones (i.e., a melodic interval). Results indicated that participants were sensitive to the differences in interval size presented: Ratings were significantly higher when two pitches differed by 7 semitones than when they differed by 6 semitones. However, ratings were also dependent on whether the interval was high or low in intensity, whether it increased or decreased in intensity across the two pitches, and whether the interval was ascending or descending in pitch. Such influences illustrate that the perception of pitch relations does not always adhere to a logarithmic function as implied by their musical labels, but that identical intervals are perceived as substantially different in size depending on other attributes of the sound source.     

The effect of intensity on relative pitch

In two experiments, we examined the effect of intensity and intensity change on judgements of pitch differences or interval size. In Experiment 1, 39 musically untrained participants rated the size of the interval spanned by two pitches within individual gliding tones. Tones were presented at high intensity, low intensity, looming intensity (up-ramp), and fading intensity (down-ramp) and glided between two pitches spanning either 6 or 7 semitones (a tritone or a perfect fifth interval). The pitch shift occurred in either ascending or descending directions. Experiment 2 repeated the conditions of Experiment 1 but the shifts in pitch and intensity occurred across two discrete tones (i.e., a melodic interval). Results indicated that participants were sensitive to the differences in interval size presented: Ratings were significantly higher when two pitches differed by 7 semitones than when they differed by 6 semitones. However, ratings were also dependent on whether the interval was high or low in intensity, whether it increased or decreased in intensity across the two pitches, and whether the interval was ascending or descending in pitch. Such influences illustrate that the perception of pitch relations does not always adhere to a logarithmic function as implied by their musical labels, but that identical intervals are perceived as substantially different in size depending on other attributes of the sound source.     

Context sensitivity and invariance in perception of octave-ambiguous tones

Three experiments investigated the influence of unambiguous (UA) context tones on the perception of octave-ambiguous (OA) tones. In Experiment 1, pairs of OA tones spanning a tritone interval were preceded by pairs of UA tones instantiating a rising or falling interval between the same pitch classes. Despite the inherent ambiguity of OA tritone pairs, most participants showed little or no priming when judging the OA tritone as rising or falling. In Experiments 2 and 3, participants compared the pitch heights of single OA and UA tones representing either the same pitch class or being a tritone apart. These judgments were strongly influenced by the pitch range of the UA tones, but only slightly by the spectral center of the OA tones. Thus, the perceived pitch height of single OA tones is context sensitive, but the perceived relative pitch height of two OA tones, as described in previous research on the “tritone paradox,” is largely invariant in UA tone contexts.     

Responsiveness of Western adults to pitch-distributional information in melodic sequences

Responsiveness of musically trained and untrained adults to pitch-distributional information in melodic contexts was assessed. In Experiment 1, melodic contexts were pure-tone sequences, generated from either a diatonic or one of four nondiatonic tonesets, in which pitch-distributional information was manipulated by variation of the relative frequency of occurrence of tones from the toneset. Both the assignment of relative frequency of occurrence to tones and the construction of the (fixed) temporal order of tones within the sequences contravened the conventions of western tonal music. A probe-tone technique was employed. Each presentation of a sequence was followed by a probe tone, one of the 12 chromatic notes within the octave. Listeners rated the goodness of musical fit of the probe tone to the sequence. Probe-tone ratings were significantly related to frequency of occurrence of the probe tone in the sequence for both trained and untrained listeners. In addition, probe-tone ratings decreased as the pitch distance between the probe tone and the final tone of the sequence increased. For musically trained listeners, probe-tone ratings for diatonic sequences tended also to reflect the influence of an internalized tonal schema. Experiment 2 demonstrated that the temporal location of tones in the sequences could not alone account for the effect of frequency of occurrence in Experiment 1. Experiment 3 tested musically untrained listeners under the conditions of Experiment 1, with the exception that the temporal order of tones in each sequence was randomized across trials. The effect of frequency of occurrence found in Experiment 1 was replicated and strengthened.     

Rear-view perception in driving: Distance information is privileged in the selection of safe gaps

Selecting a safe gap before merging into the traffic is a crucial driving skill that relies on images provided by rear-view mirrors or, recently, camera-monitor systems. When using these visual aids, some drivers select dangerously small gaps to cut in front of faster vehicles. They may do so because they base their decision either on information about distance or object size, or on miscalculated information about time-to-passage (TTP). Previous experiments have been unable to compare the role of TTP, speed, and distance information for drivers’ gap selection, as they did not investigate them in the same experimental regime. The present experiments seek to determine the perceptual variables that guide drivers’ rearward gap selection. Using short videos of an approaching vehicle filmed from three different camera heights (low, conventional, high), a total of 61 subjects either made gap safety decisions (Experiment I), or estimated the TTP, speed, and distance of an approaching vehicle (Experiment II). An effect of camera height was found for gap selection, TTP, and distance estimation, but not for speed estimation. For the high camera position, smaller gaps were selected as safe, TTP estimates were longer, and the distance to the approaching vehicle was perceived as farther. An opposite pattern was found for the low camera. Regression analyses suggested that distance is an important player. The subjects strongly relied on distance information when estimating TTP, and perceived distance dominated subjects’ gap selection. Thus, drivers seem to employ distance-based strategies when selecting safe gaps in rear-view mirrors or monitors.