Selective attention to visual compound stimuli in squirrel monkeys (Saimiri sciureus).

Area of Science:

• Cognitive psychology
• Animal behavior
• Neuroscience

Background:

• Understanding stimulus control is crucial for analyzing learning and decision-making.
• Visual compound stimuli present challenges in isolating component control.
• Previous research has not fully elucidated the differential control of form and color in simultaneous discrimination tasks.

Purpose of the Study:

• To measure the excitatory and inhibitory control of form and color components in visual compound stimuli.
• To investigate the effects of reversed reinforcement contingencies on stimulus control.
• To assess the impact of a forced delay on impulsive responding.

Main Methods:

• Five squirrel monkeys were trained on a simultaneous discrimination task with compound visual stimuli.
• Excitatory and inhibitory control were measured using unreinforced test trials with recombined stimulus components.
• Reinforcement contingencies were reversed mid-experiment to assess condition effects.

Main Results:

• Color acquired greater excitatory control than form under original reinforcement conditions.
• No significant difference in excitatory control was found under reversed conditions.
• Inhibitory control did not differ between form and color, and was less pronounced than excitatory control overall.
• A 4-second response delay significantly reduced impulsive responding.

Conclusions:

• Color is a more potent stimulus for excitatory control than form in this paradigm.
• Reinforcement contingency reversal impacts stimulus control, diminishing initial component biases.
• A forced delay is an effective strategy for reducing impulsive responding, with potential applications for neurodevelopmental disorders.