Slow eye movements reflect human decision-making about visual motion direction B S Krishna, E Poland, S Glim, B Eichelberger, S Treue |
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Cognitive Neuroscience Laboratory, German Primate Center, Germany
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| The random-dot-motion (RDM) task, which tests motion signal detection in noise, has proved extremely useful in the study of sensory decision-making. Neuronal recordings in monkeys have revealed how motion-direction information is accumulated between stimulus onset and a monkey’s decision. However, a non-invasive and easily-measured variable that reflects the dynamics of decision-making in humans at a fine temporal scale remains to be found. Here, we evaluate whether slow eye movements (SEMs) in humans viewing a RDM pattern are correlated with their ongoing decision-making process, inspired by the known parallels between motion perception and SEMs (like smooth pursuit). Human subjects viewed a low-coherence RDM pattern moving in one of two directions and indicated their decision about motion direction using either a keyboard press or a saccade. Independent of response modality, their eyes slowly moved (“drifted”) in the direction of the impending decision. Trials with SEMs were associated with better performance and greater confidence in judgment. SEMs showed a pattern similar to that of the neural activity of single neurons in monkey parietal cortex reported in the literature. SEMs may thus provide a window into decision-making and allow the testing of motion-processing models with high temporal resolution. |
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