Pigeons’ performance in a tracking change-signal procedure is consistent with the independent horse-race mode

In many cognitive tasks where humans are thought to rely on executive functioning, pigeons' behavior can be explained by associative processes. A key form of executive functioning is inhibiting prepotent responses, often investigated in humans by means of "Stop-Signal" or "Change-Signal" procedures. In these procedures, execution of a well-practiced ("Go") response to a stimulus is occasionally interrupted by a signal to withhold or alter the practiced response. Performance in such tasks is usually described by the "independent horse horse-race model." This model assumes that the processes that cause the Go and inhibitory responses occur independently; the process that finishes first determines the response observed. We further tested this model by training pigeons to track the circular movement of a colored patch around a touchscreen by pecking it; the spot occasionally deviated from its normal path (the Change signal). The pigeons had to inhibit the habitual movement of their heads to land a peck on the spot in its unexpected position. The key predictions of the independent horse-race model were confirmed in the pigeons' latency data. Thus, the independent race model can also successfully describe Stop-change performance of subjects that do not rely on executive control.