PT - JOURNAL ARTICLE AU - Drugowitsch, Jan AU - Moreno-Bote, Rubén AU - Churchland, Anne K. AU - Shadlen, Michael N. AU - Pouget, Alexandre TI - The Cost of Accumulating Evidence in Perceptual Decision Making AID - 10.1523/JNEUROSCI.4010-11.2012 DP - 2012 Mar 14 TA - The Journal of Neuroscience PG - 3612--3628 VI - 32 IP - 11 4099 - http://www.jneurosci.org/content/32/11/3612.short 4100 - http://www.jneurosci.org/content/32/11/3612.full SO - J. Neurosci.2012 Mar 14; 32 AB - Decision making often involves the accumulation of information over time, but acquiring information typically comes at a cost. Little is known about the cost incurred by animals and humans for acquiring additional information from sensory variables due, for instance, to attentional efforts. Through a novel integration of diffusion models and dynamic programming, we were able to estimate the cost of making additional observations per unit of time from two monkeys and six humans in a reaction time (RT) random-dot motion discrimination task. Surprisingly, we find that the cost is neither zero nor constant over time, but for the animals and humans features a brief period in which it is constant but increases thereafter. In addition, we show that our theory accurately matches the observed reaction time distributions for each stimulus condition, the time-dependent choice accuracy both conditional on stimulus strength and independent of it, and choice accuracy and mean reaction times as a function of stimulus strength. The theory also correctly predicts that urgency signals in the brain should be independent of the difficulty, or stimulus strength, at each trial.