Does temporal preparation facilitate visual processing in a selective manner? Evidence from attentional capture

The present study addressed the question of whether temporal preparation influences perceptual stimulus processing in a selective manner. In three visual search experiments, we examined whether temporal preparation aids spatial selection and thus reduces distraction caused by the onset of a task-irrelevant item. In each trial, participants had to detect a target amongst five non-targets and report a basic feature of the target. In some trials, an additional task-irrelevant singleton item (abrupt onset) appeared on the screen which distracted attention away from the target. To manipulate the degree of distraction, we varied the spatial distance and the stimulus-onset asynchrony between target and singleton. Temporal preparation for the target varied by means of constant foreperiods of different lengths. Though we observed overall faster responding in the case of high temporal preparation in all three experiments, temporal preparation did not reduce spatial distraction by the abrupt onset, even when the spatial position of the target was predictable. In sum, this pattern of results does not provide support for an influence of temporal preparation on spatial selection. Instead, it indicates that temporal preparation affects early visual processing in a non-selective manner.     

The perceptual onset of musical tones

The perceptual onset of a musical tone can be defined as the moment in time at which the stimulus is first perceived. In the present experiments, a simple threshold model for the perceptual onset was applied. A paradigm was used in which a sequence of tones had to be adjusted in such a way that the onsets were perceived at equally spaced moments in time. In Experiment 1, the threshold model was applied in a design in which the rise times of the tones were varied. We concluded that the perceptual onsets of the tones can, indeed, be defined as the times at which the envelopes pass a relative threshold of 15 dB below the maximum level of the tones (82 dB). In Experiment 2, the maximum levels of the tones were varied from 37 to 77 dB. The results show that there is a shift in the relative threshold, but that this shift is small relative to the shift in the stimulus level. In Experiment 3, the effect of level above masked threshold on the perceptual onset was investigated in more detail by varying the level of a background noise. The results show that the relative threshold decreases with increasing level above masked threshold. The results from our experiments strongly suggest that the relative threshold is linearly dependent on the level above masked or absolute threshold and that a 7-dB increment of this level results in a 1-dB relative threshold decrement. The threshold model is compared with a current temporal integration model for the perceptual onset of tones. It is shown that our data cannot be adequately explained by temporal integration. Our experimental results suggest that adaptation of the hearing mechanism to a certain relative stimulus level is responsible for perceptual onset. The applicability of our threshold model in various realistic musical situations is discussed.     

Effects of clock monitoring on electroencephalographic activity: is unconscious movement initiation an artifact of the clock?

Electroencephalographic (EEG) activity was recorded while participants waited to make spontaneous key-press movements (Experiment 1) or waited for tones in a pitch judgment task (Experiment 2). In one condition of each experiment, participants also had to report the position of a spot traveling on a clock at the crucial time point (i.e., when they decided to move or when the tone was presented), mimicking a procedure used to assess the time of conscious awareness of an event of interest. In a second condition, there was no clock or temporal judgment. Average EEG activity preceding key presses was substantially different when participants had to monitor the clock than when they did not. Smaller clock-related differences in average EEG activity were also present preceding tone onsets. The effects of clock monitoring on EEG activity could be responsible for previous reports that movement-related brain activity begins before participants have consciously decided to move (e.g., Libet, Gleason, Wright, & Pearl, 1983).     

Crossmodal facilitation of masked visual target identification

In the present study, participants identified the location of a visual target presented in a rapidly masked, changing sequence of visual distractors. In Experiment 1, we examined performance when a high tone, embedded in a sequence of low tones, was presented in synchrony with the visual target and observed that the high tone improved visual target identification, relative to a condition in which a low tone was synchronized with the visual target, thus replicating Vroomen and de Gelder's (2000, Experiment 1) findings. In subsequent experiments, we presented a single visual, auditory, vibrotactile, or combined audiotactile cue with the visual target and found similar improvements in participants' performance regardless of cue type. These results suggest that crossmodal perceptual organization may account for only a part of the improvement in participants' visual target identification performance reported in Vroomen and de Gelder's original study. Moreover, in contrast with many previous crossmodal cuing studies, our results also suggest that visual cues can enhance visual target identification performance. Alternative accounts for these results are discussed in terms of enhanced saliency, the presence of a temporal marker, and attentional capture by oddball stimuli as potential explanations for the observed performance benefits.     

Switching attention between the ears to monitor tones Nigel Harvey

Alternating dichotic presentation of tones was compared with monaural presentation in two different perceptual tasks. When Ss were asked to detect higher frequency target tones in fists of six background tones, they missed less than 5%. However, when the presentation was fast (10/sec) and the tones alternated dichotically, Ss reported “hearing” only three or four tones. In two further experiments, Ss were asked to judge the number of tones or to report their spatial and temporal positions; these tasks were much less accurately performed, for the dichotic lists, than the target detection task. The differing effects of switching rate on these tasks are discussed in relation to the types of processing they require.     

Implicit expectations influence target detection in children and adults

When a sound occurs at a predictable time, it gets processed more efficiently. Predictability of the temporal structure of acoustic inflow has been found to influence the P3b of event‐related potentials in young adults, such that highly predictable compared to less predictable input leads to earlier P3b peak latencies. In our study, we wanted to investigate the influence of predictability on target processing indexed by the P3b in children (10–12 years old) and young adults. To do that, we used an oddball paradigm with two conditions of predictability (high and low). In the High‐predictability condition, a high‐pitched target tone occurred most of the time in the fifth position of a five‐tone pattern (after four low‐pitched non‐target sounds), whereas in the Low‐predictability condition, no such rule was implemented. The target tone occurred randomly following 2, 3, 4, 5, or 6 non‐target tones. In both age groups, reaction time to predictable targets was faster than to non‐predictable targets. Remarkably, this effect was largest in children. Consistent with the behavioral responses, the onset latency of the P3b response elicited by targets in both groups was earlier in the predictable than the unpredictable conditions. However, only the children had significantly earlier peak latency responses for predictable targets. Our results demonstrate that target stimulus predictability increases processing speed in children and adults even when predictability was only implicitly derived by the stimulus statistics. Children did have larger effects of predictability, seeming to benefit more from predictability for target detection.     

On the nature of phase attraction in sensorimotor synchronization with interleaved auditory sequences

In a task that requires in-phase synchronization of finger taps with an isochronous sequence of target tones that is interleaved with a sequence of distractor tones at various fixed phase relationships, the taps tend to be attracted to the distractor tones, especially when the distractor tones closely precede the target tones [Repp, B. H. (2003a). Phase attraction in sensorimotor synchronization with auditory sequences: Effects of single and periodic distractors on synchronization accuracy. Journal of Experimental Psychology: Human Perception and Performance, 29, 290-309]. The present research addressed two related questions about this distractor effect: (1) Is it a function of the absolute temporal separation or of the relative phase of the two stimulus sequences? (2) Is it the result of perceptual grouping (integration) of target and distractor tones or of simultaneous attraction to two independent sequences? In three experiments, distractor effects were compared across two different sequence rates. The results suggest that absolute temporal separation, not relative phase, is the critical variable. Experiment 3 also included an anti-phase tapping task that addressed the second question directly. The results suggest that the attraction of taps to distractor tones is caused mainly by temporal integration of target and distractor tones within a fixed window of 100-150 ms duration, with the earlier-occurring tone being weighted more strongly than the later-occurring one.     

A PRP-study to determine the locus of target priming effects

Visual stimuli that are made invisible by a following mask can nonetheless affect motor responses. To localize the origin of these target priming effects we used the psychological refractory period paradigm. Participants classified tones as high or low, and responded to the position of a visual target that was preceded by a prime. The stimulus onset asynchrony (SOA) between both tasks varied. In Experiment 1 the tone task was followed by the position task and SOA dependent target priming effects were observed. When the visual position task preceded the tone task in Experiment 2, with short SOA the priming effect propagated entirely to the tone task yielding faster responses to tones on visually congruent trials and delayed responses to tones on visually incongruent trials. Together, results suggest that target priming effects arise from processing before and at the level of the central bottleneck such as sensory analysis and response selection.     

Attention‐shift vs. response‐priming explanations for the spatial cueing effect in cross‐modal tasks

The task‐irrelevant spatial location of a cue stimulus affects the processing of a subsequent target. This “Posner effect” has been explained by an exogenous attention shift to the spatial location of the cue, improving perceptual processing of the target. We studied whether the left/right location of task‐irrelevant and uninformative tones produces cueing effects on the processing of visual targets. Tones were presented randomly from left or right. In the first condition, the subsequent visual target, requiring response either with the left or right hand, was presented peripherally to left or right. In the second condition, the target was a centrally presented left/right‐pointing arrow, indicating the response hand. In the third condition, the tone and the central arrow were presented simultaneously. Data were recorded on compatible (the tone location and the response hand were the same) and incompatible trials. Reaction times were longer on incompatible than on compatible trials. The results of the second and third conditions are difficult to explain with the attention‐shift model emphasizing improved perceptual processing in the cued location, as the central target did not require any location‐based processing. Consequently, as an alternative explanation they suggest response priming in the hand corresponding to the spatial location of the tone. Simultaneous lateralized readiness potential (LRP) recordings were consistent with the behavioral data, the tone cues eliciting on incompatible trials a fast preparation for the incorrect response and on compatible trials preparation for the correct response.     

Interference effects in tone memory

Memory for a standard tone in comparison to a subsequent test tone was examined in three experiments with three intervening tones between the standard and test tones. In each trial, the intervening tones were presented from one of seven frequency range and distance from the standard tone conditions. Experiment 1 tone patterns were played at four different presentation rates, and the subjects judged whether the test was higher or lower than the standard. Memory interference effects caused by the different intervening tone conditions could be accounted for by a directional shift in the standard tone memory toward the intervening tones and by a general decrease in the standard tone memory strength with more distant intervening tones. Interference effects were smaller for the rapid presentation rates because the intervening tones formed separate "perceptual streams." Two additional experiments presented the tone patterns in a task requiring the subjects to match a continuously variable tone to their memory of the standard (Experiment 2) and a task requiring them to judge whether the standard and test tones were the "same" or "different" (Experiment 3). These experiments showed large differences in interference effects as a function of the required judgment and the subjects' musical experience.     

A model of top-down gain control in the auditory system

To evaluate a model of top-down gain control in the auditory system, 6 participants were asked to identify 1-kHz pure tones differing only in intensity. There were three 20-session conditions: (1) four soft tones (25, 30, 35, and 40 dB SPL) in the set; (2) those four soft tones plus a 50-dB SPL tone; and (3) the four soft tones plus an 80-dB SPL tone. The results were well described by a top-down, nonlinear gain-control system in which the amplifier’s gain depended on the highest intensity in the stimulus set. Individual participants’ identification judgments were generally compatible with an equal-variance signal-detection model in which the mean locations of the distribution of effects along the decision axis were determined by the operation of this nonlinear amplification system.     

Auditory negative priming in speeded reactions and temporal order judgements

Two experiments are reported that demonstrate negative priming for auditory stimuli. Reaction times and temporal order judgements were used as the dependent measures in Experiments 1 and 2, respectively. In Experiment 1, participants classified tones presented to one ear as wind or string instruments while ignoring tones presented to the other ear. The task was identical for both the prime and the subsequent probe presentations. Probe reactions were slower for previously ignored tones than for tones that had not occurred during the prime presentation. Probe reactions to previously attended tones were faster than reactions to nonrepeated tones. In Experiment 2, the probe reactions were replaced by temporal order judgements. The probability of accepting a tone as antecedent was lower for previously ignored primes than for new tones. No difference was observed between previously attended and new tones. The results are compatible with the conclusion that distractor inhibition is a necessary component of the processes that bring about observable negative priming phenomena.     

Distorted subjective reports of stimulus onsets under dual-task conditions: Delayed conscious perception or estimation bias?

We investigated whether selecting a response for one task delays the conscious perception of another stimulus (delayed conscious perception hypothesis). In two experiments, participants watched a revolving clock hand while performing two tasks in close succession (i.e. a dual-task). Two stimuli were presented with varying stimulus onset asynchrony (SOA). After each trial, participants separately estimated the onsets of the two stimuli on the clock face. Across two experiments and four conditions, we manipulated response requirements and assessed their impact on perceived stimulus onsets. Results showed that (a) providing speeded responses to the stimuli did lead to greater SOA-dependent misperceptions of both stimulus onsets as compared to a solely perceptual condition, and (b) that response grouping reduced these misperceptions. Overall, the results provide equivocal evidence for the delayed conscious perception hypothesis. They rather suggest that participants’ estimates of the two stimulus onsets are biased by the interval between their responses.     

Repetition priming in music

The authors explore priming effects of pitch repetition in music in 3 experiments. Musically untrained participants heard a short melody and sang the last pitch of the melody as quickly as possible. Each experiment manipulated (a) whether or not the tone to be sung (target) was heard earlier in the melody (primed) and (b) the prime-target distance (measured in events). Experiment 1 used variable-length melodies, whereas Experiments 2 and 3 used fixed-length melodies. Experiment 3 changed the timbre of the target tone. In all experiments, fast-responding participants produced repeated tones faster than nonrepeated tones, and this repetition benefit decreased as prime-target distances increased. All participants produced expected tonic endings faster than less expected nontonic endings. Repetition and tonal priming effects are compared with harmonic priming effects in music and with repetition priming effects in language.     

The role of timing deviations and target position uncertainty on temporal attending in a serial auditory pitch discrimination task

Listeners were presented with sequences of tones that ascended in semitone intervals. On each trial a single target tone in the sequence was displaced in pitch, and listeners were required to indicate whether the target tone was higher or lower than its normal pitch. Task constraints, specifically target serial position uncertainty and the probabilistic relationship between time deviations and target tones, were varied in order to determine the impact of task constraints on temporal attending strategy. When listeners had no advance knowledge of the serial position of the target, and early and late targets provided information regarding target serial position, performance was better for early and late target trials than for on-time target trials (Experiment 1). When listeners had no advance knowledge of the serial position of the target, and early and late temporal deviations provided no information regarding target serial position, performance for late target trials was superior to that for early and on-time target trials (Experiment 2). Finally, when target serial position uncertainty was eliminated, performance was equivalent across all three levels of target timing (early, on time, late). The results indicate that performance profiles based on stimulus timing properties are affected by various task constraints as well as by stimulus properties.     

Temporal parameters and time course of perceptual latency priming

Visual stimuli (primes) reduce the perceptual latency of a target appearing at the same location (perceptual latency priming, PLP). Three experiments assessed the time course of PLP by masked and, in Experiment 3, unmasked primes. Experiments 1 and 2 investigated the temporal parameters that determine the size of priming. Stimulus onset asynchrony was found to exert the main influence accompanied by a small effect of prime duration. Experiment 3 used a large range of priming onset asynchronies. We suggest to explain PLP by the Asynchronous Updating Model which relates it to the asynchrony of 2 central coding processes, preattentive coding of basic visual features and attentional orienting as a prerequisite for perceptual judgments and conscious perception.     

Effects of Phonetic Similarity in the Identification of Mandarin Tones

Tonal languages differ in how they use phonetic correlates e.g. average pitch height and pitch direction, for tonal contrasts. Thus, native speakers of a tonal language may need to adjust their attention to familiar or unfamiliar phonetic cues when perceiving non-native tones. On the other hand, speakers of a non-tonal language may need to develop sensitivity to tonal correlates absent from their native system. The current study examines and compares five language groups’ perception of two synthesized Mandarin tones: the high level tone and the high falling tone. It aims to examine how listeners from tonal and non-tonal backgrounds identify and categorize acoustically equidistant pitches varying along two phonetic dimensions: pitch onset and slope. Results reveal “universal” perceptual patterns across groups and also tendencies caused by native tonal systems. Our findings confirm that L1 tonal and prosodic systems affect speakers’ sensitivity to novel perceptual cues and their abilities to discern relevant phonetic differences.     

Studies in auditory timing: 1. Simple patterns

Listeners' accuracy in discriminating one temporal pattern from another was measured in three psychophysical experiments. When the standard pattern consisted of equally timed (isochronic) brief tones, whose interonset intervals (IOIs) were 50, 100, or 200 msec, the accuracy in detecting an asynchrony or deviation of one tone in the sequence was about as would be predicted from older research on the discrimination of single time intervals (6%-8% at an IOI of 200 msec, 11%-12% at an IOI of 100 msec, and almost 20% at an IOI of 50 msec). In a series of 6 or 10 tones, this accuracy was independent of position of delay for IOIs of 100 and 200 msec. At 50 msec, however, accuracy depended on position, being worst in initial positions and best in final positions. When one tone in a series of six has a frequency different from the others, there is some evidence (at IOI = 200 msec) that interval discrimination is relatively poorer for the tone with the different frequency. Similarly, even if all tones have the same frequency but one interval in the series is made twice as long as the others, temporal discrimination is poorer for the tones bordering the longer interval, although this result is dependent on tempo or IOI. Results with these temporally more complex patterns may be interpreted in part by applying the relative Weber ratio to the intervals before and after the delayed tone. Alternatively, these experiments may show the influence of accent on the temporal discrimination of individual tones.     

Sound enhances visual perception: cross-modal effects of auditory organization on vision

Six experiments demonstrated cross-modal influences from the auditory modality on the visual modality at an early level of perceptual organization. Participants had to detect a visual target in a rapidly changing sequence of visual distractors. A high tone embedded in a sequence of low tones improved detection of a synchronously presented visual target (Experiment 1), but the effect disappeared when the high tone was presented before the target (Experiment 2). Rhythmically based or order-based anticipation was unlikely to account for the effect because the improvement was unaffected by whether there was jitter (Experiment 3) or a random number of distractors between successive targets (Experiment 4). The facilitatory effect was greatly reduced when the tone was less abrupt and part of a melody (Experiments 5 and 6). These results show that perceptual organization in the auditory modality can have an effect on perceptibility in the visual modality.     

Tonal hierarchy representations in auditory imagery

Two experiments investigated psychological representations of musical tonality in auditory imagery. In Experiment 1, musically trained participants heard a single tone as a perceptual cue and built an auditory image of a specified major tonality based on that cue; participants’ images were then assessed using judgments of probe tones. In Experiment 2 participants imaged a minor tonality rather than a major one. Analysis of the probe tone ratings indicated that participants successfully imaged both major and minor tonal hierarchies, demonstrating that auditory imagery functions comparably to auditory perception. In addition, the strength of the major tonal image was dependent upon the pitch and tonal relations of the perceptual cue and the to-be-imaged tonality. Finally, representations of minor tonal hierarchies were less robust than those of major ones, converging with perceptual evidence that minor tonalities are less psychologically stable than major tonalities.