Training delays reduce the choose-short effect with keylight duration samples in pigeons

Pigeons were trained to matching 2- and 8-s keylight samples. The delay on training trials was either 0s (group 0sF), 2s (group 2sF), or varied between 1 and 3s (M=2s, group 2sV). Testing at delays of 10 and 20s revealed a choose-short tendency in all three groups. The magnitude of this tendency was largest in group 0sF and was highly similar in magnitude in groups 2sF and 2sV. In Experiment 2, the training delay remained at 0s in group 0sF and was increased to 5s in group 2sF (now group 5sF). Group 2sV (now group 5sV) received variable training delays ranging from 2 to 8s (M=5s). Testing at a 20-s delay and at a delay that exceeded the training delay by 15s for each group revealed a robust choose-short effect only in group 0sF. Groups 5sF and 5sV both demonstrated a weak and statistically nonsignificant choose-short tendency. When different durations of keylight are employed as samples, training with a nonzero delay, whether fixed or variable, reduces the magnitude of the choose-short effect, with longer training delays producing a greater reduction in the choose-short effect.