Document Type


Degree Name

Master of Science (MSc)




Faculty of Science

First Advisor

Angelo Santi

Advisor Role

Thesis Supervisor


Studies with humans and non-human animals have established how stimulus properties play an important role in the subjective duration of time. A phenomenon referred to as the Filled Interval Illusion has been found with humans, which demonstrates that filled intervals are perceived to be longer than empty intervals of equivalent duration. Recently, it has been demonstrated that pigeons judge empty time intervals bounded by two 500-ms light markers to be longer than an equivalent filled interval of light. Experiment 1 was able to replicate the Empty Interval Illusion with pigeons. Experiment 2 attempted to determine whether the Empty Interval Illusion was due to decreased attentional resources being given to timing filled intervals of light by creating an equal opportunity for filled and empty intervals to be distracted away from timing. Results demonstrated an overall general decrease in matching accuracy for empty intervals during psychophysical testing. Experiment 3 changed the markers that bound empty intervals so that matching accuracy for anchor durations would improve. Results correspond to a memory mixing process with domination of filled intervals being present in reference memory.

Convocation Year


Convocation Season


Included in

Psychology Commons