Signalled free-operant avoidance of shock by pigeons pecking a key.

Researchers worked with pigeons that could peck a key to delay electric shocks.

A warning light came on before shock periods. The team varied how long the light stayed on.

They watched whether birds pecked more during the warning or during safe periods.

Birds pecked fastest when the warning light was on.

Short warning lights made pecking look like unsignaled avoidance.

The signal length changed how the birds acted, not just whether a signal existed.

Shimp et al. (1971) showed pigeons prefer signaled over unsignaled avoidance. The new study adds that even signaled avoidance can act like unsignaled if the signal is too brief.

Dove et al. (1974) proved key pecks trained with food can switch to shock avoidance. Lobb et al. (1977) now shows those same pecks come under tight stimulus control once the avoidance is running.

Tager-Flusberg (1981) later used brief keylights for food reinforcement and saw respondent pecking. The 1977 shock study mirrors this, showing brief signals evoke quick responses no matter the reinforcer type.

If you use warning stimuli in treatment or animal training, keep the signal long enough for the learner to notice and act. Ultra-brief cues may erase the safety value of the signal and drive frantic, unsignaled-like responding. Test duration in your own setup and watch for response bursts that look uncontrolled.