Is choice bias in delayed matching a consequence of inter-trial interval effects?

Area of Science:

• Cognitive Psychology
• Animal Behavior
• Behavioral Neuroscience

Background:

• Inter-trial intervals (ITIs) in behavioral experiments can influence choice behavior, potentially confounding results.
• Previous research suggests ITIs can induce choice biases in delayed matching-to-sample tasks.
• The specific role of delay duration and ambient conditions on choice, independent of ITIs, requires further investigation.

Purpose of the Study:

• To investigate the effects of delay duration on choice behavior in a delayed matching-to-sample task without inter-trial intervals.
• To examine how ambient lighting conditions during the delay period influence choice biases.
• To determine if choice biases can emerge solely as a function of delay and environmental factors.

Main Methods:

• Sixteen pigeons were trained on a symbolic matching-to-sample task with varying sample durations (3s vs. 9s).
• A delay (2.5s, 5s, 10s, 20s) was introduced between sample presentation and comparison stimuli, with no inter-trial intervals.
• Two delay conditions were tested: darkness (Group Light Off) and illumination by a houselight (Group Light On).

Main Results:

• In the Light Off condition, matching accuracy decreased with increasing delay for both short and long samples.
• In the Light On condition, matching accuracy remained high for short samples but decreased significantly for long samples as delay increased, indicating a "choose-short" effect.
• Choice biases emerged even in the absence of inter-trial intervals, influenced by delay length and lighting.

Conclusions:

• Choice biases in delayed matching-to-sample tasks can occur independently of inter-trial intervals.
• Ambient lighting conditions during the delay period significantly modulate choice behavior.
• The duration of the delay and sample length interact to produce specific choice biases, such as the "choose-short" effect.