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

Schneider BA, Parker S, Murphy D - Atten Percept Psychophys (2011)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, ON, L5L 1C6, Canada. bruce.schneider@utoronto.ca

ABSTRACT
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.

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The probability of a baseline stimulus being correctly identified given that it followed a baseline (BS) stimulus minus the probability of a baseline stimulus being correctly identified given that it followed an added stimulus (AS), as a function of session block when the added stimulus had a sound pressure level of 50 dB SPL (baseline + 50 condition) and when the added stimulus was 80 dB SPL (baseline + 80 condition). Data are presented for each individual in the experiment
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Fig3: The probability of a baseline stimulus being correctly identified given that it followed a baseline (BS) stimulus minus the probability of a baseline stimulus being correctly identified given that it followed an added stimulus (AS), as a function of session block when the added stimulus had a sound pressure level of 50 dB SPL (baseline + 50 condition) and when the added stimulus was 80 dB SPL (baseline + 80 condition). Data are presented for each individual in the experiment

Mentions: To examine whether the improvement seen in Fig. 2 was affected by where, in the trial sequence, the added loud stimulus appeared, we looked to see whether there was a difference in percent correct identification for the four baseline stimuli when they followed a baseline stimulus versus when they followed an added stimulus. Figure 3 plots, for each of the 6 participants, the difference between the percentage of times a baseline stimulus (25, 30, 35, 40 dB SPL) was correctly identified when it followed a baseline stimulus and the percentage of times a baseline stimulus was correctly identified when it immediately followed an added stimulus, as a function of block number. This figure suggests that this difference did not change over blocks of sessions in either the B + 50 or the B + 80 dB condition. This figure also suggests that in the B + 50 condition, but not in the B + 80 condition, participants, on average, performed better when a baseline stimulus followed another baseline stimulus than when it followed an added stimulus. A within-subjects ANOVA on the data from the B + 50 condition confirmed that the difference scores in this condition did not differ across blocks, F(3,15) = 2.04, p = .152, and that they were significantly different from 0, F(1,5) = 8.85, p = .031. The equivalent ANOVA on the data from the B+80 condition again failed to show a significant effect of trial block, F(3,15) = 1.46, p = .265, and could not reject the hypothesis that the mean difference score was equal to 0, F(1,5) = 2.33, p = .187. Hence, the difference scores changed little over blocks, and only the difference scores for the B+50 condition differed significantly from zero.Fig. 3


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

Schneider BA, Parker S, Murphy D - Atten Percept Psychophys (2011)

The probability of a baseline stimulus being correctly identified given that it followed a baseline (BS) stimulus minus the probability of a baseline stimulus being correctly identified given that it followed an added stimulus (AS), as a function of session block when the added stimulus had a sound pressure level of 50 dB SPL (baseline + 50 condition) and when the added stimulus was 80 dB SPL (baseline + 80 condition). Data are presented for each individual in the experiment
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3118000&req=5

Fig3: The probability of a baseline stimulus being correctly identified given that it followed a baseline (BS) stimulus minus the probability of a baseline stimulus being correctly identified given that it followed an added stimulus (AS), as a function of session block when the added stimulus had a sound pressure level of 50 dB SPL (baseline + 50 condition) and when the added stimulus was 80 dB SPL (baseline + 80 condition). Data are presented for each individual in the experiment
Mentions: To examine whether the improvement seen in Fig. 2 was affected by where, in the trial sequence, the added loud stimulus appeared, we looked to see whether there was a difference in percent correct identification for the four baseline stimuli when they followed a baseline stimulus versus when they followed an added stimulus. Figure 3 plots, for each of the 6 participants, the difference between the percentage of times a baseline stimulus (25, 30, 35, 40 dB SPL) was correctly identified when it followed a baseline stimulus and the percentage of times a baseline stimulus was correctly identified when it immediately followed an added stimulus, as a function of block number. This figure suggests that this difference did not change over blocks of sessions in either the B + 50 or the B + 80 dB condition. This figure also suggests that in the B + 50 condition, but not in the B + 80 condition, participants, on average, performed better when a baseline stimulus followed another baseline stimulus than when it followed an added stimulus. A within-subjects ANOVA on the data from the B + 50 condition confirmed that the difference scores in this condition did not differ across blocks, F(3,15) = 2.04, p = .152, and that they were significantly different from 0, F(1,5) = 8.85, p = .031. The equivalent ANOVA on the data from the B+80 condition again failed to show a significant effect of trial block, F(3,15) = 1.46, p = .265, and could not reject the hypothesis that the mean difference score was equal to 0, F(1,5) = 2.33, p = .187. Hence, the difference scores changed little over blocks, and only the difference scores for the B+50 condition differed significantly from zero.Fig. 3

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, ON, L5L 1C6, Canada. bruce.schneider@utoronto.ca

ABSTRACT
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.

Show MeSH