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Perceptual discrimination in static and dynamic noise: the temporal relation between perceptual encoding and decision
Roger Ratcliff1, Philip L Smith
1Department of Psychology, The Ohio State University, Columbus, OH 43210, USA. ratcliff.22@osu.edu
Journal of Experimental Psychology. General
|February 4, 2010
Summary
Noise impacts perceptual decision-making onset differently across tasks. In letter tasks, noise delays evidence accumulation, suggesting a time-locked process to stimulus feature encoding, unlike brightness tasks.
Area of Science:
- Cognitive Psychology
- Neuroscience
- Perception
Background:
- Understanding the temporal dynamics of perceptual processing is crucial for explaining decision-making.
- Factors influencing the onset and course of decision-making remain an active area of research.
Purpose of the Study:
- To investigate how noise affects the time course of perceptual processing and subsequent decision-making.
- To determine if noise influences the onset of decision-making or the rate of evidence accumulation.
Main Methods:
- Conducted 9 new experiments and reanalyzed 3 published studies.
- Used letter-discrimination and brightness-discrimination tasks with degraded stimuli (static and dynamic noise).
- Quantified decision onset and time course using the diffusion model.
Main Results:
- Dynamic noise significantly shifted response-time distributions in letter discrimination, indicating delayed decision onset.
- Static noise had a smaller effect on letter discrimination and minimal effect on brightness discrimination.
- Noise-delayed decision onset in letter tasks, contrary to predictions of solely reduced evidence accumulation rates.
Conclusions:
- Decision-making onset is influenced by noise, particularly in tasks requiring complex feature encoding like letter discrimination.
- The onset of evidence accumulation appears time-locked to the perceptual encoding of stimulus features.
- Noise affects decision-making by delaying the start of evidence accumulation, not just by slowing its rate.
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