The perceived tempi of coherent and streaming tone sequences

Previous research has demonstrated that a sequence of tones that is alternated between ears is stretched out in echoic memory, as compared with monaural sequences. Although the stimulus onset asynchronies (SOAs) were the same in the interaural and monaural conditions, the perceptual onset asynchronies (POAs) differed by 24 msec. The present study investigated whether an analogous perceptual phenomenon exists for frequency-alternating tone sequences. It turned out that the POAs of coherent and even of streaming tone sequences were precisely the same as with nonalternating tone sequences.     

The perceived tempi of coherent and streaming tone sequences: II

Previous research demonstrated, by means of a reaction time technique, that there is no difference between the perceptual onset asynchronies (POAs) of nonalternating tone sequences and of frequency-alternating tone sequences, even if the latter are streaming. This finding implies that listeners are capable of extracting the tempo of the total alternating sequence, even though successive tones belong to different streams. The present study investigated whether subjects are also capable of establishing the tempo of one stream. To this end, listeners were required to match the rate of one stream by adjusting the rate of a nonalternating comparison stream (a pulse sequence). In addition, they were required to match the total rate of the streaming sequence. It turned out that the total tempo could be matched precisely and that the tempo of one stream could be approximated very closely.     

The detection of anisochrony in monaural and interaural sound sequences

Nakao and Axelrod (1976) and van Noorden (1975) showed that the threshold for discriminating an anisochronous duple rhythm (a series of clicks with a temporal offset on every other one) from an isochronous rhythm (no offset) is poorer when the clicks are presented alternately to the two ears than when they are presented to the same ears. Van Noorden reported that the difference between the thresholds in the alternating and nonalternating conditions varied with the tempo of the sequence. Nakao and Axelrod found invariance of this threshold difference with sequence speed. According to our quantification of temporal processing of interaural sequences, the latter result should be expected. We carried out five psychophysical experiments to establish interaural and monaural discrimination between isochronous and anisochronous rhythms. Across experiments, base time intervals of 60–720 msec were spanned. The main result was that we replicated the poorer discrimination for interaural sequences. This deterioration in discrimination was the same for all sequence speeds. It was also the case that the thresholds were almost constant up to a sound repetition rate of about 3 per second, but increased linearly with slower rates. This result supports evidence in the literature that temporal processing of sequences faster than about 3–4 sounds per second differs from temporal processing of slower sequences.     

Sensorimotor synchronization with chords containing tone-onset asynchronies

Musical ensemble performance requires the synchronization of multiple performers, resulting in sequences of chords containing multiple tones with multiple onsets. Experiments 1 and 2 investigate whether sensorimotor synchronization with chord sequences containing tone-onset asynchronies is affected by (1) the magnitude of these asynchronies (25, 30, or 50 msec) and (2) the pitch of the leading tone (high vs. low). Participants tapped a finger in synchrony with different types of chord sequences created by crossing these variables, as well as with sequences of chords containing simultaneous onsets. Results indicate that taps were drawn toward the second onset, when present, especially when it was lower in pitch than the first. Additionally, chords with nonsimultaneous onsets increased tapping variability for nonmusicians, but decreased variability for musicians. Experiment 3 measured the perceptual centers of the chords from Experiment 2, and yielded results suggesting that subjective onsets determine the temporal placement of taps during synchronization.     

Assignment of Leadership Role Changes Performers' Gaze During Piano Duo Performances

This study investigated modulation of gaze and synchronization in piano duos under manipulation of the leader-follower relationship. Three pairs of pianists played under 3 conditions: reversed leader/follower roles and one where neither was leader or follower. The primo and second players could see one another through a glass window but could hear only the sounds of the pianos. We analyzed each performer's gaze toward the coperformer frame by frame and measured asynchrony between performers. The main findings are that (a) gaze was altered in the presence of leadership assignments-followers' and leaders' gaze durations lengthened and shortened, respectively; (b) mutual gaze just before tempo changes enhanced synchronization regardless of leadership condition; and (c) the asynchronies of tone onset at the moment of a tempo change under the leader/follower conditions did not significantly differ from that under the control condition.     

An anxiety-related bias in semantic activation when processing threat/neutral homographs

Three experiments are reported comparing high and low-trait anxious subjects in terms of their patterns of semantic activation in response to ambiguous primes, with one threat-related and one neutral meaning. Such primes were followed by targets related to either their threat or neutral meaning, or by unrelated targets, in a lexical decision task. Experiments 1 to 3 employed stimulus onset asynchronies (SOAs) of 750 msec, 500 msec, and 1250 msec, respectively. At 500-msec SOA all subjects showed facilitation for both meanings. At 750-msec SOA the only significant priming effect was that for the threat-related meaning in the high-anxiety group, and a similar trend was found at 1250-msec SOA. Consideration of the patterns of priming for targets following ambiguous threat/neutral primes suggest that at the longer SOAs, high-anxiety subjects consciously “lock on” to a threatening interpretation if one has been made available by earlier automatic spreading activation.     

Variation in cue duration reveals top-down modulation of involuntary orienting to uninformative symbolic cues

This article reports three experiments in which the effects of cue duration on involuntary orienting to uninformative symbolic cues (arrows presented at fixation) were investigated. Experiment 1 showed that symbolic cues had less effect on involuntary orienting when they were presented for only 25 msec than when they were presented for 200 msec across a range of stimulus onset asynchronies. Experiment 2 suggested that the effect of cue duration on involuntary orienting was due primarily to top-down strategic factors, rather than to bottom-up stimulus factors, and Experiment 3 suggested that these strategic factors may involve differences in how the cue is processed. Altogether, the present findings are important because they emphasize the distinction between cue processing and the putative involuntary orienting that results from such processing in the symbolic-cuing paradigm. In so doing, the present results help resolve discrepant findings that have been reported across previous studies.     

Bidirectional semantic priming in the attentional blink

The time course of semantic priming between two associated words was tracked using rapid serial visual presentation of two synchronized streams of stimuli appearing at about 20 items/sec, each stream including a target word. The two words were semantically related or unrelated and were separated by stimulus onset asynchronies (SOAs) of 0–213 msec. Accuracy in reporting the first target (T1) versus the second target (T2) has been shown to interact dramatically with SOA over this range. The materials were in English in Experiment1 and Italian in Experiment2. T1 was semantically primed only at short SOAs, whereas T2 was primed at all SOAs (Experiment 1) or at all SOAs except the shortest one (Experiment2). The results indicate a strong competition between target words early in processing, with T2 often becoming the first word identified at short SOAs, thus priming T1.     

Semantic activation in the absence of perceptual awareness

Participants performed a semantic categorization task on a target that was preceded by a prime word belonging either to the same category (20% of trials) or to a different category (80% of trials). The prime was presented for 33 msec and followed either immediately or after a delay by a pattern mask. With the immediate mask, reaction times (RTs) were shorter on related than on unrelated trials. This facilitatory priming reached significance at prime-target stimulus onset asynchronies (SOAs) of 400 msec or less and remained unaffected by task practice. With the delayed mask, RTs were longer on related than on unrelated trials. This reversed (strategic) semantic priming proved to be significant (1) only at a prime-target SOA of 400 msec or longer and (2) after the participants had some practice with the task. The present findings provide further evidence that perceiving a stimulus with and without phenomenological awareness can lead to qualitatively different behavioral consequences.     

Effects of contrast polarity in paracontrast masking

The visibility of a target stimulus can be suppressed (inhibition) or increased (facilitation) during paracontrast masking. Three processes have been proposed to be involved in paracontrast masking: brief inhibition, facilitation, and prolonged inhibition (Breitmeyer et al., 2006). Brief inhibition is observed when the mask precedes the target at short stimulus onset asynchronies (SOAs) ranging from -10 to -30 msec, whereas prolonged inhibition is effective up to very large SOAs of -450 msec. Facilitation, enhancement in target visibility, can be observed at SOA values between -20 and -110 msec. We further investigated these processes by changing target-mask spatial separation and the contrast polarity of the mask. Our results show that (1) facilitation weakens when spatial separation between the target and mask is increased or when they have opposite contrast polarity, and (2) brief inhibition turns into facilitation for the opposite-polarity mask, whereas prolonged inhibition does not change significantly. These results suggest a fast inhibition mechanism realized in the contrast-specific center-surround antagonism of classical receptive fields for brief inhibition and a slower, higher level cortical processing that is indifferent to contrast polarity for prolonged inhibition.     

Auditory temporal discrimination by trained listeners

Previous reports from this laboratory have shown that untrained listeners cannot name the order of sounds in extended sequences of unrelated items such as hisses, tones, and buzzes at item durations of 200 msec, even though identification of order for the sounds of speech and music is accomplished readily at much shorter item durations. The present study indicates that under appropriate conditions subjects can be trained to distinguish between and to identify permuted orders within sequences of nonrelated sounds each lasting only 10 msec or less. Evidence is presented suggesting that much of what passes for direct identification of order is actually based on prior identification of a larger pattern. Two principal mechanisms seem to mediate discrimination of auditory temporal order: (1) fine resolution (requiring prior training) permitting identification of over-all patterns and capable of operating with item durations of only a few msec; (2) coarse resolution (special prior training not required) allowing naming of order of items having minimal durations usually above 200 msec for unfamiliar sequences.     

Effect on numerosity judgment of grouping of tones by auditory channels

Previous research suggests that numerosity judgments for sequences of tones improve when the sequence is structured such that equal and small groups of tones alternate between the ears. The present. study systematically investigates the effects of the structure of tone sequences on number judgment. Tone frequency is chosen as the grouping principle instead of spatial location. In the first experiment, sequences with equal groups of 2, 3, 4, 5, 6, or 7 tones (groups alternating between 800 and 1, 250 Hz) were compared with monotonous sequences. At a slow repetition rate of the tones (280 msec onset to onset), grouping the sequence deteriorated the numerosity judgment. At II fast repetition rate of the tones (100 msec onset to onset) grouping improved numerosity judgment, but only if the group size did not exceed 4 to 5 tones. In the second experiment, the equality of group size in the sequence as a necessary condition for the improvement was investigated. It was found that tone sequences comprised of equal groups were judged more accurately in number than sequences comprised of unequal groups. These results seem to give support for the existence of an auditory subitizing process. The results of this study are also compared with the results of studies in which sequences of tones, alternating one by om! between locations or frequencies, had to be judged in number.     

Look away! Eyes and arrows engage oculomotor responses automatically

The present study investigates how people’s voluntary saccades are influenced by where another person is looking, even when this is counterpredictive of the intended saccade direction. The color of a fixation point instructed participants to make saccades either to the left or right. These saccade directions were either congruent or incongruent with the eye gaze of a centrally presented schematic face. Participants were asked to ignore the eyes, which were congruent only 20% of the time. At short gaze—fixation-cue stimulus onset asynchronies (SOAs; 0 and 100 msec), participants made more directional errors on incongruent than on congruent trials. At a longer SOA (900 msec), the pattern tended to reverse. We demonstrate that a perceived eye gaze results in an automatic saccade following the gaze and that the gaze cue cannot be ignored, even when attending to it is detrimental to the task. Similar results were found for centrally presented arrow cues, suggesting that this interference is not unique to gazes.     

Picking up the pace: effects of global temporal context on sensitivity to the tempo of auditory sequences

This article continues a line of research examining factors affecting listeners' auditory tempo sensitivities. Of particular interest is the question of whether listeners are sensitive to the overall (global) pace of their auditory environment and how this sensitivity may affect their perceptions of sequence timing. To address this question, we manipulated the set of sequence tempi (between 300 and 700 msec) that listeners experienced over the course of a 1-h period (i.e., the global temporal context) while they performed a tempo-discrimination task involving standard-comparison pairs of isochronous tone sequences. Overall findings show systematic distortions in perceived tempo that are consistent with the view that listeners adapt to the global pace of their auditory environments. Moreover, general support was found for the hypothesis that increasing the number of equal intervals in a standard sequence produces greater improvements in tempo sensitivity when the standard sequence tempo is different from the global pace than when it is at the global pace. Implications of these findings for models of timing and temporal processing are discussed.     

Preferred perceptual tempo for sound sequences: comparison of adults, children, and infants

Previous motor and perceptual tasks have found optimal processing for sound sequences of a rate of around 600 msec. IOI (Interonset Interval). This zone of optimal processing (the rate at which discrimination is optimal) slows with age and is also found with infants. The current work investigated whether listeners "prefer" sequences at the rate for which they demonstrate optimal processing. In the present study, three experiments were done. Exp. 1 measured tempo preferences in adults who listened to pairs of isochronous sound sequences varying in tempo (from 100- to 1500-msec. IOI) and were required to indicate which they preferred. As expected, highest preferences were expressed for the intermediate tempi, supporting the hypothesis of a zone of preferred tempi comparable to the zone of optimal processing. Moreover, this preference for intermediate tempi was not affected by the temporal context (absence of differences between a fast, a slow, and a wide set of tempi). In Exp. 2, the same procedure was applied to 6- and 10-yr.-olds. Children in both groups had systematic preferences for the fastest tempi within a set, and the older children generally preferred slower sequences. Exp. 3 used a preference paradigm for sound sequences with 4-mo.-old infants, comparing sequences of 100- vs 300-msec. IOI, 300- vs 900-msec. IOI, and 100- vs 900-msec. IOI. No systematic tempo preferences were observed. We conclude that tempo discrimination and tempo preference may have some commonality (perhaps related to a zone of optimal processing), especially in adults, but that they also involve quite distinct processes which undergo different developmental sequences. Whereas adults prefer what they process the best, children prefer what is fastest (and therefore more attention-getting), and we have not been able to detect preferences in infants.     

Modality effects in rhythm processing: Auditory encoding of visual rhythms is neither obligatory nor automatic

Modality effects in rhythm processing were examined using a tempo judgment paradigm, in which participants made speeding-up or slowing-down judgments for auditory and visual sequences. A key element of stimulus construction was that the expected pattern of tempo judgments for critical test stimuli depended on a beat-based encoding of the sequence. A model-based measure of degree of beat-based encoding computed from the pattern of tempo judgments revealed greater beat sensitivity for auditory rhythms than for visual rhythms. Visual rhythms with prior auditory exposure were more likely to show a pattern of tempo judgments similar to that for auditory rhythms than were visual rhythms without prior auditory exposure, but only for a beat period of 600 msec. Slowing down the rhythms eliminated the effect of prior auditory exposure on visual rhythm processing. Taken together, the findings in this study support the view that auditory rhythms demonstrate an advantage over visual rhythms in beat-based encoding and that the auditory encoding of visual rhythms can be facilitated with prior auditory exposure, but only within a limited temporal range. The broad conclusion from this research is that “hearing visual rhythms” is neither obligatory nor automatic, as was previously claimed by Guttman, Gilroy, and Blake (2005).     

Rate of information segregation in developmentally dyslexic children

Slowed processing of sequential perceptual information is related to developmental dyslexia. We investigated this unimodally and crossmodally in developmentally dyslexic children and controls ages 8-12 years. The participants judged whether two spatially separate trains of brief stimuli, presented at various stimulus onset asynchronies (SOA) in one or two senses, were synchronous or not. The stimulus trains consisted of light flashes in vision, clicks in audition, and indentations of the skin in the tactile sense. The dyslexic readers required longer SOAs than controls for successful performance in all six comparisons. The crossmodal spatiotemporal resolution of the groups differed more than unimodal performance. The dyslexic readers' segregation performance was also less differentiated than that of the controls. Our results show that not only sensory but also polysensory nonverbal information processing is temporally impaired in dyslexic children.     

Observer weighting of interaural delays in filtered impulses

Onset dominance in sound localization was examined by estimating observer weighting of interaural delays for each click of a train of high-frequency filtered clicks. The interaural delay of each click was a normal deviate that was sampled independently on each trial of a single-interval design. In Experiment 1, observer weights were derived for trains ofn=2, 4, 8, or 16 clicks as a function of interclick interval (ICI=1.8, 3.0, or 12.0 msec). For smalln and short ICI (1.8 msec), the ratio of onset weight to remaining weights was as large as 10. As ICI increased, the relative onset weight was reduced. For largen and all ICIs, the ongoing train was weighted more heavily than the onset. This diminishing relative onset weight with increasing ICI andn is consistent with optimum distribution of weights among components. Efficiency of weight distribution is near ideal when ICI=12 msec andn=2 and very poor for shorter ICIs and larger ns. Further experiments showed that: (1) onset dominance involves both within- and between-frequency-channel mechanisms, and (2) the stimulus configuration (ICI,n, frequency content, and temporal gaps) affects weighting functions in a complex way not explained by cross-correlation analysis or contralateral inhibition (Lindemann, 1986a, 1986b).     

Multimodal access to verbal name codes

Congruent information conveyed over different sensory modalities often facilitates a variety of cognitive processes, including speech perception (Sumby & Pollack, 1954). Since auditory processing is substantially faster than visual processing, auditory-visual integration can occur over a surprisingly wide temporal window (Stein, 1998). We investigated the processing architecture mediating the integration of acoustic digit names with corresponding symbolic visual forms. The digits "1" or "2" were presented in auditory, visual, or bimodal format at several stimulus onset asynchronies (SOAs; 0, 75, 150, and 225 msec). The reaction times (RTs) for echoing unimodal auditory stimuli were approximately 100 msec faster than the RTs for naming their visual forms. Correspondingly, bimodal facilitation violated race model predictions, but only at SOA values greater than 75 msec. These results indicate that the acoustic and visual information are pooled prior to verbal response programming. However, full expression of this bimodal summation is dependent on the central coincidence of the visual and auditory inputs. These results are considered in the context of studies demonstrating multimodal activation of regions involved in speech production.     

Two types of auditory sequence perception

It has been suggested recently that there are two fundamentally distinct types of auditory sequence perception in man: (1) hofistic pattern recognition (HPR), operating for component item durations from a few milliseconds up to about 200 msec; and (2) direct identification of components and their order (Direct ICO), requiring verbal encoding of names for constituent sounds and requiring item durations roughly 200 msec and above for extended sequences. The present study, using only the very first judgments from 795 untrained participants presented with recycled three-item sequences, provided data consistent with this dichotomous formulation. In addition, it appeared that separate bursts of a noise band generated on-line were treated as different components in HPR and could not be used for sequence matching; “frozen” noise bursts having identical microstructure were treated as the same component and permitted HPR. On-fine noise bursts permitted Direct ICO, with naming based on long-term spectral characteristics of noise.