[Speech discrimination. Regulation of amplification in the inner ear].
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Animals↗
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Generalized oddity performance in preschool children: a bimodal training procedure.
Oddity performance requires relational discriminative responding, which typically is difficult to establish in children with MAs below five. In Experiment 1, a combination intrasubject reversal and multiple baseline across subjects design was used to establish the internal validity of a bimodal intervention in establishing generalized oddity performance. Six of seven children demonstrated oddity responding when presented with stimuli that instantiated the oddity relation in the visual and auditory modalities simultaneously. Oddity performance was evaluated with both reversal assessments and assessments with new sets of stimuli. The newly acquired oddity performance was durable; the six children continued to respond discriminatively when returned to a visual-only task on which they previously had been unsuccessful. Utilizing a reversal assessment more stringent than that of Experiment 1, Experiment 2 replicated this effect. The present studies are the first to demonstrate the utility of bimodal training in establishing oddity performance. The bimodal procedure is discussed with respect to the theoretical positions of Gibson, Dinsmoor, and Dixon.
Attention↗
EEG and slow cortical potentials in anticipation of mental tasks with different hemispheric involvement.
Mental arithmetic is supposed to be processed by the left hemisphere, while pattern matching has been considered to be processed by the right hemisphere. These different mental tasks were presented to 16 right-handed male subjects. As a variable task difficulty was varied for the two task categories. The task presentations were preceded by 6 sec warning stimuli which indicated the level of difficulty of the task. EEG and slow cortical potentials (SCPs) were recorded from temporal and precentral leads of both hemispheres. The reference was noncephalic. During the anticipation interval beta-activity was enhanced above the hemisphere primarily involved in the particular task. SCPs failed to show a comparable clear pattern. A late negative component showed task-dependent asymmetries prior to easy tasks, but not prior to difficult tasks.
Adolescent↗
Operant conditioning of P300.
This study demonstrates that operant conditioning may increase the P300 component of the event-related potential above a level obtained without contingent training. An experimental group of subjects was rewarded for producing large P300 amplitudes and was compared with a yoked control group which was rewarded on a random basis. During training the experimental subjects increased both the amplitude of the P300 and of a subsequent frontal negative slow wave relative to the control group. These training effects were independent of prestimulus potential shifts and occurred likewise for target and nontarget stimuli.
Adult↗
Strongly focused attention and auditory event-related potentials.
Effects of selective attention on the auditory event-related potential were studied by delivering two tones in a rapid, randomized sequence. One of the tones was designated as relevant and the other as irrelevant, the subject's task being to discriminate occasional softer tones within the relevant tones. Relevant and irrelevant tones differed from each other either in location (left vs. right ear) or pitch (300 vs. 6000 Hz). In both conditions, relevant tones elicited a larger N1 deflection (peak latency about 120 ms) than did irrelevant tones. In contrast to the exogenous N1 elicited by unattended tones, the scalp distribution of this attentional "N1 effect" did not depend on the stimulated ear and, further, its amplitude was not affected by the frequency of attended tones. These results suggest that the present attention effect was caused, at least mainly, by an endogenous processing negativity rather than by an enhancement of exogenous N1 components.
Adult↗
Operant conditioning after temporal lobe lesions in man: conditional and simple discrimination learning.
Temporal lobe lesions have been found to impair the acquisition of classical conditional discrimination learning in an eyelid conditioning paradigm, with sparing of simple eyelid conditioning. In the present study, subjects with left or right temporal resections were compared with normal controls on two operant conditioning tasks using a conditional and a simple discrimination paradigm analogous to the previously reported classical conditioning tasks. Subjects with right temporal lesions, and to a lesser extent those with left temporal lesions, were impaired relative to frontal lobe and control subjects in the acquisition of a conditional discrimination within an operant conditioning setting. A subsequent experiment showed that both left and right temporal lobe subjects were unimpaired on a simple operant discrimination task. These findings are compatible with theory relating hippocampal function to the learning of if-then rules.
Adult↗
Left hemispheric dipole locations of the neuromagnetic mismatch negativity to frequency, intensity and duration deviants.
The aim of the current study was to differentiate the sources of neuromagnetic mismatch negativity (MMNm) to deviants of different features. For this purpose, the MMNm of twenty-one healthy subjects (seven males) were recorded left-hemispherically. Subjects were stimulated monaurally in an oddball paradigm with standard tones of 1000 Hz and three different kinds of mismatch tones (frequency, duration and intensity deviants). Data analysis revealed mean MMNm dipole locations anterior, inferior and more medial than the N100m dipoles. The mean difference between the N100m and MMNm dipoles was in the range of up to 6 mm in one dimension. The dipole locations of all three kinds of deviants differed significantly from each other. The MMNm dipoles of both frequency and duration deviants were found to be significantly inferior to the corresponding source of intensity deviants, while the MMNm dipoles of duration and frequency deviants significantly differed in anterior-posterior direction. This differentiation between sources emphasizes the importance of feature analysis in MMN(m) generation.
Acoustic Stimulation↗
Hippocampal cells have behavioral correlates during the performance of an auditory working memory task in the rat.
Single unit activity was recorded from the rat hippocampal CA1 and CA3 subfields, dentate gyrus (DG), entorhinal cortex (EC), subicular complex (SB), motor cortex (MC), prefrontal cortex (PFC), and dorsomedial thalamus (DMT) during performance of a continuous non-matching-to-sample task. The rats made go and no-go responses to indicate whether the current tone was the same as (match) or different from (nonmatch) the preceding tone. About half of the units from the MC, CA1, CA3, and DG had motor correlates, increments of activity immediately prior to a go response. This suggests that those regions are involved in making a response. The CA1 and CA3 had more units with comparison-motor correlates, increases of activity prior to a correct go response on nonmatch trials. This pattern of activity suggests that the CA1 and CA3 are involved in a mnemonic process of comparison between retained and current stimuli in a nonspatial auditory task.
Animals↗
Perceptual units in speech recognition.
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Acoustic Stimulation↗
Free-operant comparisons of wild and domestic Norway rats.
Wild and domestic rats (Rattus norvegicus) were compared on nondifferential appetitive variable interval responding, discrimination, and discrimination reversal procedures. The effects of strain, sex, deprivation, preexperimental handling, and sessions on response rate were examined. Performances during the 60 days of variable interval training showed prolonged increases over that period for all strain-sex groupings, with domestic subjects responding at higher rates than wild. Males also tended to respond at higher rates than females. During the discrimination procedure wild subjects showed more resistance to extinction than did the domestic subjects, although these differences generally diminished after the 30 days of training. During the discrimination reversal procedure domestic subjects reversed their responding pattern more readily than did the wild subjects, and domestic females reached criterion significantly sooner than domestic males. The effects of deprivation and handling were not significant during the experimental procedures.
Animals↗
Low-frequency vowel formant discrimination in hearing-impaired listeners.
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Audiometry↗
Frequency discrimination in the adapted ear.
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Adaptation, Physiological↗
Ubiquity of hyperacuity.
A decision as to whether two line segments are colinear, as on a vernier scale (--/-- vs --/--), can be made with high sensitivity by the human visual system. Just-noticeable vernier displacement is much smaller than the separation required to resolve two parallel lines, i.e., to perceive them as two lines rather than one. Vernier acuity is thus also called "hyperacuity." Similar effects have been discovered in bat echolocation, for discrimination of a range-jittered point target from a nonjittered target, in the jamming avoidance response (JAR) of electric fish, and in differential pitch sensitivity experiments with human subjects. Are jitter sensitivity in echolocation, JAR in electroreception, differential pitch sensitivity in audition, and vernier acuity in vision based on the same general principle? The results in this article indicate that such phenomena are indeed similar from the viewpoint of detection theory, and that experimental performance can be used to behaviorally estimate auditory parameters such as bandwidth, beamwidth, and temporal resolution, as well as to test different signal processing models without resort to masking. Applications of the hyperacuity effect to radar, sonar, and medical ultrasound are suggested.
Animals↗
The length of the retention interval, forgetting, and subjective similarity.
A long retention interval tends to result in the poor retention known as forgetting. A high subjective similarity between stimuli frequently produces their poor retention. Thus, a long retention interval may increase the subjective similarity between stimuli (the RIISS hypothesis), and this increase may produce forgetting. To examine this hypothesis, college students made speeded same-different discriminations between two lines or tones of different lengths or frequencies that were 400 ms or 3,300 ms apart, and they rated the similarity of these stimuli. The long interval produced poorer overall performance as expected, but also produced poorer performance on different than same stimuli, implying that it increased the subjective similarity between the initial and subsequent stimuli, and it also increased rated similarity, in support of the RIISS hypothesis. The position that stored stimuli lose less common information than distinctive information explains RIISS evidence better than does perturbation theory.
Attention↗
Periodicity pitch perception of retarded children.
In order to expand the body of information concerning auditory function in the presence of the generalized cortical dysfunction associated with severe mental retardation, the discrimination of periodicity pitch signals by nonverbal severely retarded children and adults of normal intelligence was examined using an operant conditioning adaptation of the psychophysical method of constant stimulus differences. The periodicity pitch difference limens (DLs) based on changes in repetition rate were compared with frequency DLs obtained from low (150 Hz) and high frequency (2200 Hz) sinusoids. Periodicity pitch signals were generated by gating a 2200-Hz sinusoid over a range from 141 to 159 pulses per sec and passing the signals through a narrow band-pass filter to ensure no low frequency energy was present. The DLs (75% correct discriminations) were computed from the three types of discrimination performance curves. Standard errors of the means were small and retarded subjects showed good test-retest reliability. The results indicated that the simple and complex pitch discrimination abilities for both normal and retarded subjects were similar.
Adult↗
A note on possible culture-bound effects in frequency discrimination.
Tanner and Rivette [J. Acoust. Soc. Am. 36, 1465--1467 (1964)] reported that three native speakers of Punjabi were unable to discriminate frequency differences an order of magnitude greater than the usual DL's for frequency. This paper is often cited as evidence for culture-bound effects in frequency discrimination. We obtained frequency DL estimates from 34 observers comprising a number of linguistic groups, including Punjabi. No evidence of disability in frequency discrimination was found in any of the groups.
Culture↗
Limits of auditory patterns discrimination for patterns with various durations and numbers of components.
In three experiments, listeners' abilities to detect changes in randomly generated tonal sequences were determined for sequences or "patterns" ranging in total duration from 62.5 ms to 2 s. Experiment 1 utilized an adaptive-tracking procedure, with n, the number of pattern components, as the dependent variable, and included a variety of spectral and temporal discrimination tasks with isochronous patterns. When the to-be-detected change was the only variation on a given dimension (e.g., the presence or location of a brief pause), patterns were discriminable when the absolute duration of the changed element, or pause, exceeded a critical value. However, when each pattern component varied on the dimension of the to-be-detected change (e.g., frequency), discriminability was strongly related to the number of tones in the pattern, and only weakly to the durations of either the target components or the total pattern. This dependence of discrimination performance on n was also demonstrated with anisochronous patterns in experiment 2. Experiment 3 revealed the same dependence of performance on the number of components per pattern as did experiments 1 and 2, but with delta f/f as the dependent variable, rather than n. The number of pattern components and the proportional duration of the target components, relative to total pattern duration, were confounded in these experiments. Additional research is therefore required to determine whether number or proportional target-tone duration is the primary determinant of pattern discriminability.
Adult↗
Intensity discrimination in forward masking.
A nonmonotonic intensity discrimination function was recently reported in which a midlevel hump occurred for 25-ms sinusoidal standards ranging from 20 to 100 dB SPL and presented 100 ms after an intense narrow-band noise forward masker [F.-G. Zeng et al., Hear. Res. 55, 223-230 (1991)]. This paper provides additional data on how the midlevel hump is affected by three factors of forward masking: signal delay, masker level, and frequency. Specifically, just-noticeable differences (jnd's) in intensity were obtained at signal delays of 50, 200, and 400 ms. Results show that at the midlevels the forward-masked intensity jnd's did not recover to their unmasked values, even at the 400-ms signal delay. The longer the signal delay, the smaller this midlevel hump. This slow recovery of the midlevel jnd's is consistent with the finding that low-spontaneous rate (SR) neurons have a slow recovery from forward masking [E. M. Relkin and J. R. Doucet, Hear. Res. 55, 215-222 (1991)]. The large midlevel effect decreased sharply as masker level was reduced from 90 to 60 dB SPL, and disappeared for masker levels less than 40 dB SPL. A frequency selectivity effect for the large midlevel jnd effect was also observed, as maskers with frequency components 2 to 3 oct away from the signal frequency did not affect the jnd's. Overall, the present data are consistent with the hypothesis of Zeng et al. (1991) that low-SR neurons are involved in the midlevel hump of intensity discrimination in forward masking.
Adult↗