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.     

Effect of practice on the identification of auditory sequences

Using a variant of the up-and-down method to establish duration thresholds for correct report of the order of sound sequences, six experiments were run with a practiced crew of three Ss. All showed striking improvement with practice, but substantial individual differences were observed. Two Ss found spaced sequences harder than simple cyclic ones and single presentations hardest of all, had increased difficulty when the component frequencies were brought closer together, and were disturbed by irregular timing. These variables made no difference to the third and most sensitive S, whose threshold reached 23 msec per component. All Ss displayed poorer performance if noise, additional signals, or a distrating activity occurred between the stimulus sequence and the response.     

Increasing capacity: practice effects in absolute identification

In most of the long history of the study of absolute identification--since Miller's (1956) seminal article--a severe limit on performance has been observed, and this limit has resisted improvement even by extensive practice. In a startling result, Rouder, Morey, Cowan, and Pfaltz (2004) found substantially improved performance with practice in the absolute identification of line lengths, albeit for only 3 participants and in a somewhat atypical paradigm. We investigated the limits of this effect and found that it also occurs in more typical paradigms, is not limited to a few virtuoso participants or due to relative judgment strategies, and generalizes to some (e.g., line inclination and tone frequency) but not other (e.g., tone loudness) dimensions. We also observed, apart from differences between dimensions, 2 unusual aspects of improvement with practice: (a) a positive correlation between initial performance and the effect of practice and (b) a large reduction in a characteristic trial-to-trial decision bias with practice.     

Effects of an auditory model on the learning of relative and absolute timing

The effects of an auditory model on the learning of relative and absolute timing were examined. In 2 experiments, participants attempted to learn to produce a 1,000- or 1,600-ms sequence of 5 key presses with a specific relative-timing pattern. In each experiment, participants were, or were not, provided an auditory model that consisted of a series of tones that were temporally spaced according to the criterion relative-timing pattern. In Experiment 1, participants (n = 14) given the auditory template exhibited better relative- and absolute-timing performance than participants (n = 14) not given the auditory template. In Experiment 2, auditory and no-auditory template groups again were tested, but in that experiment each physical practice participant (n = 16) was paired during acquisition with an observer (n = 16). The observer was privy to all instructions as well as auditory and visual information that was provided the physical practice participant. The results replicated the results of Experiment 1: Relative-timing information was enhanced by the auditory template for both the physical and observation practice participants. Absolute timing was improved only when the auditory model was coupled with physical practice. Consistent with the proposal of D. M. Scully and K. M. Newell (1985), modeled timing information in physical and observational practice benefited the learning of the relative-timing features of the task, but physical practice was required to enhance absolute timing.     

Effects of practice and signal energy on duration discrimination of brief auditory intervals

In Experiment 1, the proposition that duration discrimination of filled auditory intervals is based on temporal information rather than on energy-dependent cues was tested in 64 naive subjects. The subjects were presented with two auditory stimuli at different levels of intensity within one trial, and had to decide which of the two was longer in duration. An adaptive psychophysical procedure was used. As a measure of performance, difference threshold estimates in relation to a 50-msec standard interval were computed. Duration discrimination showed no effect of energy values, indicating that the subjects’ discrimination was independent of stimulus intensity. The goal of Experiments 2A and 2B was to investigate the effects of practice on duration discrimination which, in addition, may provide an indirect test for the potential use of energy-dependent cues. Effects of practice on duration discrimination of filled (Experiment 2 A) and empty (Experiment 2B) intervals were studied in 6 subjects in each case, over 20 testing sessions. An adaptive psychophysical procedure that was similar to the one used in Experiment 1 was applied. Neither short-term effects of practice based on the first five testing sessions, nor long-term effects of practice based on the means of 4 consecutive weeks, could be demonstrated. The results of the present study suggest that duration discrimination of brief auditory intervals is based on temporal information and not on stimulus energy. Furthermore, implications for the notion of a very basic bio-logical timing mechanism underlying temporal processing of brief auditory intervals in the range of milliseconds are discussed.     

Gain control in the auditory system: absolute identification of intensity within and across the two ears

A number of studies have suggested that the auditory system employs nonlinear gain control to modulate its response to a broad range of stimulus intensities (e.g., Parker, Murphy, & Schneider, 2002), but the precise location and nature of this mechanism remains uncertain. To address these issues, we investigated the extent to which gain control in one ear was influenced by auditory events in the other ear. Listeners were asked to identify which of four sounds, varying in intensity (25, 30, 35, and 40 dB [SPL]), had been presented to the left ear. Subsequent test sets included an 80-dB (SPL) stimulus presented to either the left (ipsilateral) or the right (contralateral) ear. Ipsilateral presentations of the 80-dB (SPL) stimulus produced a greater reduction in identification accuracy among the original four sounds than did contralateral presentations, but both presentations caused a reduction in gain. In a second experiment, the perceived laterality of a sound was manipulated by presenting the same sound to both ears with an interaural time delay. When the 80-dB (SPL) stimulus was added to the set of quiet sounds (which were presented to both ears but were perceived to be in the left ear because of the interaural time delay), identification accuracy was reduced by the same amount, independently of whether the 80-dB (SPL) stimulus was perceived only in the ipsilateral ear or only in the contralateral ear.     

Spatial coding of auditory signals

Sequences of nine binary auditory signals (dots and dashes) were presented to 20 subjects in Experiment I. The subjects were instructed to internally organize the signals into two-dimensional arrays. Visual patterns (letters) could be recognized in these imaginary arrays in both upright and rotated orientations. In Experiment II, a group of nine subjects, which was instructed to use spatial imagery of this kind, reproduced significantly longer sequences of signals than nine control subjects. By means of internal spatial organization, experimental subjects were able to reproduce sequences up to 45 signals in length, whereas control subjects recalled near the chance level for portions of sequences longer than nine signals. Three levels of information processing were postulated to account for the results, with spatial organization occupying a mediating level between acoustic and verbal levels.     

Developmental perspectives on the localization and detection of auditory signals

Responsiveness of 1-, 3-, and 5-year-old children and adults to octave-band noises at .4 and 10 kHz was assessed with a go/no-go version of visual reinforcement audiometry (VRA) (Moore, Thompson, & Thompson, 1975) and a two-alternative, forced-choice version (Suzuki & Ogiba, 1961; Trehub, Schneider, & Endman, 1980). Infants performed better on the two-alternative, forced-choice version in quiet and in noisy backgrounds, and adults performed better on the two-alternative, forced-choice version in quiet but not in noisy backgrounds. Performance on the two tasks was essentially equivalent for 3- and 5-year-old children. Superior performance on two-alternative VRA over go/no-go may be due to lesser cognitive demands in the case of infants and to the engagement of superior decision strategies in the case of adults.     

Attending to simple auditory and visual signals

Rutgers-The State University, New Brunswick, New Jersey 08903 Is the quality of information obtained from simple auditory and visual signals diminished when both modalities must be attended to simultaneously? This question was investigated in an experiment in which subjects made forced-choice judgments of the location of simple light and tone signals presented in focused- and divided-attention conditions. The data are compared with the predictions of a model that describes the largest performance decrement to be expected in the divided-attention condition on the basis of nonattentional factors. The results of this comparison suggest that the difference in performance between focused- and dividedattention conditions is attributable solely to the increased opportunity to confuse signal with noise as the number of modalities is increased. Thus, there appears to be no evidence that dividing attention between modalities affects the quality of the stimulus representations of individual light and tone signals.     

Saccade latency and warning signals: Effects of auditory and visual stimulus onset and offset

Previous studies have found that a nonspecific visual event occurring at the fovea 50–150 msec after the onset of a peripheral target delayed the initiation of the saccade to that target. The present studies replicated and extended this finding by studying the effects of both visual and auditory warning signals, by examining the effects of onset and offset warning on manual response latency, and by investigating the effects of presenting the warning events in the periphery of the visual field. The results indicated that the interfering effects occur with visual but not auditory stimuli, with saccades but not motor responses, and when the visual warning event occurs either foveally or in the subject’s periphery. Implications for the processes involved are discussed.     

Relational and absolute cues in auditory discrimination by monkeys

Rhesus monkeys were trained to make auditory frequency, intensity, and duration discriminations. Initial training was carried out with a procedure which allowed the utilization of either relational cues or absolute cues. Later tests with similar auditory parameters allowed only the utilization of relational cues. Performance on these latter tests indicated that relational rather than absolute cues had been utilized when both types were available on the frequency and intensity discrimination tasks. However, absolute rather than relational cues were apparently utilized in making duration discriminations.     

Training the absolute identification of pitch

Two methods for training the absolute judgment of pitch, reference training and series training, were studied. Reference training concentrated during training on the identification of three reference tones in a set of nine pure tones, while series training gave equal weight during training to the identification of all nine tones. Results of pre- and posttraining tests, scored for the number of correct judgments, showed that reference training was more effective than series training for listeners with musical experience. In addition, discriminability (d′) scaling of pre- and posttest performance indicated that reference training was particularly effective for training listeners with musical experience when the nine tones of a set were grouped into three pitch classes—high, medium, and low pitch. Listeners without musical experience benefited from both training methods, but their overall improvement was less than that for musical listeners.     

Attention and auditory evoked responses to low-detectability signals

Comparisons were made between cortical evoked responses obtained under two conditions: (1) while Ss were reading, and (2) while they were attempting to count auditory signals. The amplitudes of evoked responses to low-detectability auditory stimuli were found to be approximately doubled when the Ss were required to count the number of stimuli, as compared to amplitudes recorded when they were reading. The duration of the response was also markedly increased. These increases in response amplitude and duration are considerably greater than those observed in earlierexperiments, where high-levelsignalswere used. Inter-S variability of the waveform of the averageevoked response was observed to be much less when the Ss counted the stimuli. In another experiment the level of the auditory signalwas varied over a range of approximately +4 to -4 decibels relative to the listeners’ behavioral thresholds. The per cent of signalswhich they counted varied from near-zero to 100, over this range, and the evoked response concurrently showed a variation from “unmeasureable” to approximately 8 microvolts.     

Divided attention between simultaneous auditory and visual signals

Past studies of simultaneous attention to pairs of visual stimuli have used the “dual-task” paradigm to show that identification of the direction of a change in luminance, whether incremental or decremental, is “capacity-limited,” while simple detection of these changes is governed by “capacity-free” processes. On the basis of that finding, it has been suggested that the contrast between identification and detection reflects different processes in the sensory periphery, namely the responses of magno- and parvocellular receptors. The present study questions that assertion and investigates the contribution of central processing in resource limitation by applying the dual task to a situation in which one stimulus is auditory and one is visual. The results are much the same as before, with identification demonstrating the tradeoff in performance generally attributed to a limited capacity but detection showing no loss compared with single-task controls. This implies that limitations on resources operate at a central level of processing rather than in the auditory and visual peripheries.