Date of Graduation


Document Type


Degree Type



Eberly College of Arts and Sciences



Committee Chair

Kennon A Lattal

Committee Co-Chair

Michael Perone

Committee Member

Nicholas A Turiano


It has been suggested that reinforcers of different durations can be made more discriminable by pairing specific stimulus conditions with different durations (Bonem & Crossman, 1988). The purpose of the current experiment was to assess the effects of signaling reinforcer duration prior to reinforcer onset on initial-link responding under a concurrent-chains schedule of reinforcement. Initial-link responding was assessed across two sets of reinforcer durations (2- vs. 6-s hopper access and 6- vs. 10-s hopper access) and conditions in which terminal-link stimuli were the same (e.g., both red) and different (e.g., white, blue, or yellow). Preference was defined as the key with the proportion of responses greater than 0.5. Preference for the longer-duration reinforcer occurred for three of four pigeons when presented as a choice between 2 s and 6 s. One of four pigeons preferred the longer duration reinforcer when presented with 6 s vs. 10 s. The inclusion of differential terminal-link stimuli did not enhance preference for the longer duration relative to conditions in which the terminal-link stimuli were undifferentiated across both sets of reinforcer durations.