Document Type


Degree Name

Master of Arts (MA)




Faculty of Science

First Advisor

Angelo Santi

Advisor Role

Thesis Supervisor


The mode-control model of counting and timing (Meek & Church, 1983) suggests that discriminations based on number and time may be controlled by the same internal clock mechanism. In Experiment 1, two groups of pigeons were initially trained to perform delayed symbolic matching-to-sample (DSMTS) at a 5s fixed baseline delay, with sample stimuli that consisted of sequences of flashing light. Testing was conducted with a range of delays (0, 2.5, 5, 7.5, and 10s). In the Number Group, control by number was established by varying the number of flashes while holding time constant. In the Time Group, control by time, or number, was established by varying the sample duration while holding the number of flashes constant. In Experiment l, data from the Number Group supported the mode control model, while analysis of the Time Group’s performance failed to identify whether these birds used either temporal or numerical aspects of their stimuli to control their choice of comparison. In Experiment 2, the pigeons received injections of methamphetamine (1.5 mg/kg) or saline under delay testing conditions identical to Experiment l in an attempt to determine if methamphetamine speeds up the internal clock and if the same theoretical pacemaker mechanism is responsible for memory for time and number. Data from both groups failed to support the notion that an increase in dopamine levels results in an increase in the rate of an internal pacemaker mechanism. Rather, Experiment 2 further supported the notion that amphetamine may affect attention to temporal/numerical samples in a general manner.

Convocation Year


Convocation Season