Speed and Accuracy of Visual Motion Discrimination by Rats (2013)
Speed and Accuracy of Visual Image Discrimination by Rats (2013).
Animals must continuously evaluate sensory information to select the preferable among possible actions in a
given context, including the option to wait for more information before committing to another course of action.
In experimental sensory decision tasks that replicate these features, reaction time distributions can be informative
about the implicit rules by which animals determine when to commit and what to do. We measured reaction times of
Long-Evans rats discriminating the direction of motion in a coherent random dot motion stimulus, using a self-paced
two-alternative forced-choice (2-AFC) reaction time task. Our main findings are: (1) When motion strength was constant
across trials, the error trials had shorter reaction times than correct trials; in other words, accuracy increased with
response latency. (2) When motion strength was varied in randomly interleaved trials, accuracy increased with motion strength,
whereas reaction time decreased. (3) Accuracy increased with reaction time for each motion strength considered separately,
and in the interleaved motion strength experiment overall. (4) When stimulus duration was limited, accuracy improved with
stimulus duration, whereas reaction time decreased. (5) Accuracy decreased with response latency after stimulus offset.
This was the case for each stimulus duration considered separately, and in the interleaved duration experiment overall.
We conclude that rats integrate visual evidence over time, but in this task the time of their response is governed more
by elapsed time than by a criterion for sufficient evidence.
Support: J S McDonnell Foundation, Kavli Institute for Brain and Mind