Effects of initial-link schedule on suboptimal choice are modulated by bias

Previous research suggests that longer initial-link durations decrease suboptimal choice, a relationship that has been predicted by the Signal for Good News (SiGN) model. The present study aimed to replicate these results with FR 1 and VI 20-s initial-link durations. Six pigeons responded in a concurrent-chains procedure in which one initial-link key led to a terminal-link which provided a lower overall probability of reinforcement, but included discriminative stimuli that signaled trial outcomes (suboptimal alternative), and the other led to a terminal link with higher overall probability, but did not arrange discriminative stimuli (optimal alternative). Preference for the suboptimal alternative was lower with VI 20-s schedules during initial links compared with FR 1 schedules. Such preference was modulated by key-location biases; suboptimal choice was more extreme when the suboptimal alternative was located on the key towards which pigeons were biased, relative to when it was located on the other key. Overall, predicted values of suboptimal choice from the SiGN model were similar to observed values, although some deviations were apparent due to the key-location biases. These results provide further evidence that initial-link durations influence suboptimal choice and also point to the potential influence of idiosyncratic biases on suboptimal choice.