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Results for “Pitch Discrimination”

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At least 487 records · Page 27Linked to original sources
PubMed2005

Task-set inertia and memory-consolidation bottleneck in dual tasks.

Three dual-task experiments examined the influence of processing a briefly presented visual object for deferred verbal report on performance in an unrelated auditory-manual reaction time (RT) task. RT was increased at short stimulus-onset asynchronies (SOAs) relative to long SOAs, showing that memory consolidation processes can produce a functional processing bottleneck in dual-task performance. In addition, the experiments manipulated the spatial compatibility of the orientation of the visual object and the side of the speeded manual response. This cross-task compatibility produced relative RT benefits only when the instruction for the visual task emphasized overlap at the level of response codes across the task sets (Experiment 1). However, once the effective task set was in place, it continued to produce cross-task compatibility effects even in single-task situations ("ignore" trials in Experiment 2) and when instructions for the visual task did not explicitly require spatial coding of object orientation (Experiment 3). Taken together, the data suggest a considerable degree of task-set inertia in dual-task performance, which is also reinforced by finding costs of switching task sequences (e.g., AC --> BC vs. BC --> BC) in Experiment 3.

Attention↗
PubMedDate not supplied

Effect of low level carbon monoxide on compensatory tracking and event monitoring.

Experiments by Putz et al. concerning the effect of carbon monoxide (CO) exposure on compensatory tracking and monitoring in healthy young men were replicated. Task and procedural variables were reproduced as closely as practical. Subjects were exposed to either room air or 100 ppm CO. Mean carboxyhemoglobin (COHb) levels in the high CO exposure groups were 5.1% for Putz et al. (70 ppm exposure), and 8.24% for the present study (100 ppm exposure). In both studies elevated COHb produced a statistically significant increase over time in log mean absolute deviation scores (tracking error) with respect to control groups. The magnitude of the effect was smaller in the present study, perhaps because of subtle methodological or training differences between studies. The relationship between task difficulty and magnitude of CO-induced dysfunction remains unresolved. In contrast to Putz et al., no statistically significant effect of COHb in monitoring behavior was found. The failure to replicate this feature of may reflect the large differences in baseline performance, and higher variance in the present study.

Adult↗
PubMed1975

Stimulus generalization of suppression in rats following aversively motivated instrumental or Pavlovian training.

Following 100 or 300 avoidance training trials, instrumental subjects and their yoked Pavlovian counterparts were tested for generalization of lick suppression along the frequency dimension of the avoidance conditioned stimulus. Gradients of stimulus control were evident after 300 instrumental avoidance training trials, and additional intradimensional Pavlovian discrimination training further sharpened the gradients. After 100 trials, the yoked Pavlovian subjects suppressed more than their instrumental counterparts. However, with increased Pavlovian training, flatter gradients with decreased suppression were obtained. Results from a second experiment revealed that, whereas Pavlovian experience decreased suppression to the tone, subjects suppressed drinking in the presence of static, environmental cues. Data from both experiments supported interpretations that stress the role of response control over environmental events.

Acoustic Stimulation↗
PubMed2000

Neglect between but not within auditory objects.

Unilateral neglect is frequently characterized by the presence of extinction, which is a lack of awareness to contralesional visual stimuli in the presence of those further towards the ipsilesional side. It has been established that this visual extinction can be reduced if the stimuli are grouped together into a single object. However, attention between and within auditory objects has never before been studied. We demonstrate for the first time that unilateral neglect--hitherto thought primarily to be a disorder of visuospatial processing-- involves a specific deficit in allocating attention between auditory objects separated only in time and not in space. Importantly, this deficit is restricted to comparisons between sounds: the patients' ability to make within-sound comparisons is similar to that of controls. These differences cannot be explained in terms of different time spans over which comparisons must be made. The results suggest unilateral neglect is linked to--if not actually determined by--a reduction in attentional capacity in both the visual and auditory domains, and across the dimensions of both space and time. The findings have potential clinical applications.

Acoustic Stimulation↗
PubMed1975

Blocking and overshadowing in two species of fish.

In Experiment 1, a mixed blocking-overshadowing effect of color on an auditory discrimination was demonstrated in goldfish. In Experiment 2 (with lines differing in color and angle), blocking of angle by color and of color by angle was demonstrated in goldfish, In Experiment 3 (again with lines differing in color and angle), overshadowing of angle by color was demonstrated in carp, but the same animals (like goldfish in a previous study) failed to show greater intradimensional than extradimensional transfer. These results are consistent with the hypothesis that blocking and overshadowing are general phenomena of vertebrate learning. They suggest also that the processes responsible for blocking and overshadowing are different from those which produce the dimensional transfer effect.

Acoustic Stimulation↗
PubMed2003

Seasonal changes in avian song control circuits do not cause seasonal changes in song discrimination in song sparrows.

In seasonally breeding songbirds, brain nuclei of the song control system that act in song perception change in size between seasons. It has been hypothesized that seasonal regression of song nuclei may impair song discrimination. We tested this hypothesis in song sparrows (Melospiza melodia), a species in which males share song types with neighbors and must discriminate between similar songs in territorial interactions. We predicted that song sparrows with regressed song systems would have greater difficulty in discriminating between similar songs. Sparrows were housed either on short days (SD) and had regressed song circuits, or were exposed to long days and implanted with testosterone (LD+T) to induce full growth of the song circuits. We conducted two experiments using a GO/NO-GO operant conditioning paradigm to measure song discrimination ability of each group. Birds learned four (experiment 1) or three (experiment 2) pairs of song types sequentially, with each pair more similar in the number of shared song elements and thus more difficult to discriminate. Circulating T levels differed between the SD and LD+T groups. The telencephalic song nuclei HVc, RA, and area X were larger in the LD+T birds. The two groups of sparrows did not differ, however, in their ability to learn to discriminate between shared song types, regardless of the songs' similarity. These results suggest that seasonal changes in the song control system do not affect birds' ability to make difficult song discriminations.

Animals↗
PubMed1987

Response mode and P300 from auditory stimuli.

The P300 component of the event-related brain potential (ERP) was elicited with a simple auditory discrimination task. Subjects were required to respond in three different ways to target stimuli across conditions: (1) silently counting the targets; (2) tapping their index finger every time a target was detected; or (3) pressing a button with their thumb when a target was presented. In addition, ERPs were recorded during each response mode while the subjects' eyes were either open or closed. P300 amplitude was larger for the counting compared to the tapping or button press tasks especially during the eyes closed condition. The peak latency of the P300 was longer when obtained from the counting compared to the tapping and button-press tasks for both eye conditions. Response mode also interacted with electrode site for peak latency. The results suggest that the P300 ERP component is sensitive to the nature of the subject's response during discrimination tasks.

Adult↗
PubMed1991

Psychometric functions for level discrimination.

To determine the form of psychometric functions for 2I,2AFC level discrimination (commonly called intensity discrimination), ten increment levels were presented in random order within blocks of 100 trials. Stimuli were chosen to encompass a wide range of conditions and difference limens: eight 10-ms tones had frequencies of 0.25, 1, 8, or 14 kHz and levels of 30, 60, or 90 dB SPL; two 500-ms stimuli also were tested: a 1-kHz tone at 90 dB SPL and broadband noise at 63 dB SPL. For each condition, at least 20 blocks were presented in mixed order. Results for five normal listeners show that the sensitivity, d', is nearly proportional to delta L (= 20 log [(p + delta p)/p], where p is sound pressure) over the entire range of difference limens. When d' is plotted against Weber fractions for sound pressure, delta p/p, or intensity, delta I/I, exponents of the best-fitting power functions decrease with increasing difference limens and are less than unity for large difference limens. The approximately proportional relation between d' and delta L agrees with modern multichannel models of level discrimination and with psychometric functions derived for single auditory-nerve fibers. The results also support the notion that the difference limen, expressed as delta LDL and plotted on a logarithmic scale, is an appropriate representation of performance in level-discrimination experiments.

Adult↗
PubMed1978

Changes in auditory perception in the menstrual cycle.

In a attempt to specify the critical functional components involved in the menstrual fluctuation of the upper frequency limit of the binaural beat we have obtained evidence of better performance in a variety of tasks at period and mid-cycle than at other times. These tasks include detection of physical beating, low-frequency octave matching, and lateralisation of clicks having interaural time delays in the 100 musec region. Continuous pure-tone frequency discrimination did not show a significant cyclical pattern overall but there was a tendency for low-frequency discrimination to show the described pattern. An attempt is made to reconcile some of these results with those of Wynn (1973) on absolute pitch, in terms of possible physiological and biochemical correlates. Three conclusions can be drawn: (1) The representations both of low-frequency tones and of the interaural time differences involved in some localisation tasks are particularly susceptible to alteration by the biochemical changes of the menstrual cycle: (2) The changes underlying perceptual variations are multiple, and inevitably confounded in any single task. (3) The distinction between the sensitivity and bias parameters of performance appears to be valuable in specifying menstrual effects. Several further lines of enquiry are suggested, but methodological difficulties in cycle research make it likely that more progress will come from better understanding of the physiological bases of psychoacoustic tasks using other methods, rather than from investigating natural menstrual effects.

Adult↗