Behaviour Determinants of the 'Choose-Short Effect'

Abstract

This study aimed to elucidate the mechanisms behind the behavioural phenomenon called the 'choose-short effect' by exploring the hen’s ability to discriminate temporal stimuli in delayed match-to-sample DMTS) procedure. This experiment aimed to add to the understanding of the behavioural processes that affect animals’ ability to perceive time and how an animal’s own actions can influence their perception of time. The Behaviour Theory of Timing (BeT; Killeen & Fetterman, 1988) assumes that the hens own behaviour mediates their ability to time. This assumption was tested in the present experiment by introducing a ‘response-requirement’ during the sample stimulus on a two alternative forced choice temporal discrimination. If the assumptions of BeT are correct the response requirement should increase accuracy with temporal discriminations as it can serve as discriminative stimulus signalling in the passage of time. Each hen experienced two experimental phases called ‘No-response required’ (NR) and ‘Response required’ (RR) in a DMTS procedure. In the ‘NR’ conditions the house light was illuminated for either 3 s or 9 s serving as the ‘sample’ stimuli. After the sample stimulus was presented the ‘back-key’ was illuminated and the first response to the back-key activated the choice keys after a randomly selected delay of either 0 s, 3 s, 9 s or 12 s. For the ‘RR’ condition the procedure was the same as the ‘No-light’ condition apart from the ‘back key’ was illuminated throughout the sample presentation. Results showed that there was no particular group bias towards reporting stimuli as ‘short’. However, the hens had higher accuracy in the ‘RR’ conditions when the ‘back key’ was illuminated throughout sample presentation then when it was not (‘NR’ conditions). This suggests that the animals own behaviour improved their ability to time.