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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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Percent correct, averaged over participants, as a function of session block (five sessions to a block) in three conditions: (1) when the stimulus set in the absolute identification experiment contained four tones (baseline set = {25, 30, 35, and 40 dB SPL}); (2) when the stimuli consisted of the baseline set plus a 50-dB SPL tone (B + 50); and (3) when the stimuli consisted of the baseline set plus an 80-dB SPL tone (B + 80)
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Fig2: Percent correct, averaged over participants, as a function of session block (five sessions to a block) in three conditions: (1) when the stimulus set in the absolute identification experiment contained four tones (baseline set = {25, 30, 35, and 40 dB SPL}); (2) when the stimuli consisted of the baseline set plus a 50-dB SPL tone (B + 50); and (3) when the stimuli consisted of the baseline set plus an 80-dB SPL tone (B + 80)

Mentions: Figure 2 plots the mean percentage of stimuli correctly identified over the course of the experiment (in four blocks of five sessions) in each of the three conditions. This figure indicates that the addition of a fifth stimulus (50 or 80 dB SPL) resulted in a reduction in accuracy, with the reduction being more severe the more intense the added stimulus. There is also an indication that accuracy improves over time in each of the three conditions. A two-factor, within-participants ANOVA with condition (B, B + 50, and B + 80) as the first factor and block number as the second factor (blocks 1–4, referring, respectively to sessions 1–5, 6–10, 11–15, and 16–20) confirmed that there were significant main effects due to condition, F(2,10) = 32.495, p < .001, and block number, F(3,15) = 10.343, p < .001, as well as a significant condition × block interaction, F(6,30) = 2.47, p = .046. The interaction effect is due to the fact that while percent correct increased monotonically with session block for the B and B+80 conditions, performance in the first five sessions in B+50 was better than in the second five sessions. One-tailed t-tests indicated that accuracy, collapsed across blocks, was greater in the baseline than in the B + 50 condition, t(5) = 6.410, p < .001, which, in turn, was greater than that in the B + 80 condition, t(5) = 2.41, p = .030, as was expected.Fig. 2


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

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

Percent correct, averaged over participants, as a function of session block (five sessions to a block) in three conditions: (1) when the stimulus set in the absolute identification experiment contained four tones (baseline set = {25, 30, 35, and 40 dB SPL}); (2) when the stimuli consisted of the baseline set plus a 50-dB SPL tone (B + 50); and (3) when the stimuli consisted of the baseline set plus an 80-dB SPL tone (B + 80)
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Related In: Results  -  Collection

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Fig2: Percent correct, averaged over participants, as a function of session block (five sessions to a block) in three conditions: (1) when the stimulus set in the absolute identification experiment contained four tones (baseline set = {25, 30, 35, and 40 dB SPL}); (2) when the stimuli consisted of the baseline set plus a 50-dB SPL tone (B + 50); and (3) when the stimuli consisted of the baseline set plus an 80-dB SPL tone (B + 80)
Mentions: Figure 2 plots the mean percentage of stimuli correctly identified over the course of the experiment (in four blocks of five sessions) in each of the three conditions. This figure indicates that the addition of a fifth stimulus (50 or 80 dB SPL) resulted in a reduction in accuracy, with the reduction being more severe the more intense the added stimulus. There is also an indication that accuracy improves over time in each of the three conditions. A two-factor, within-participants ANOVA with condition (B, B + 50, and B + 80) as the first factor and block number as the second factor (blocks 1–4, referring, respectively to sessions 1–5, 6–10, 11–15, and 16–20) confirmed that there were significant main effects due to condition, F(2,10) = 32.495, p < .001, and block number, F(3,15) = 10.343, p < .001, as well as a significant condition × block interaction, F(6,30) = 2.47, p = .046. The interaction effect is due to the fact that while percent correct increased monotonically with session block for the B and B+80 conditions, performance in the first five sessions in B+50 was better than in the second five sessions. One-tailed t-tests indicated that accuracy, collapsed across blocks, was greater in the baseline than in the B + 50 condition, t(5) = 6.410, p < .001, which, in turn, was greater than that in the B + 80 condition, t(5) = 2.41, p = .030, as was expected.Fig. 2

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