Effects of uncontrollable pre-aversive stimuli on positively reinforced behavioral precision

• Grant number: 24/21300-7
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: June 01, 2025
• End date: July 31, 2027
• Field of knowledge: Humanities - Psychology - Experimental Psychology
• Principal Investigator: Maria Helena Leite Hunziker
• Grantee: Gabriel Bueno Terhoch
• Host Institution: Instituto de Psicologia (IP). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Neutral stimuli that systematically precede aversive stimuli acquire the function of pre-aversive stimuli. Overlaid on positive reinforcement, pre-aversive stimuli paired with uncontrollable aversive stimuli reduce the response rate, an effect known as conditioned suppression. This effect, considered a model of anxiety, has its studies restricted to the interference in the response rate. However, varying the dimension of behavior affected by the pre-aversive stimulus in experimental studies may have both theoretical and translational importance. The present project aims to evaluate, with rats, the interference of pre-aversive stimuli on behavioral precision: a bar-press response will be considered precise if its duration is within a previously defined interval. Precise responses will be positively reinforced; responses with a duration greater or less than the established interval will not produce consequences. In Phase 1 and the others, reinforcement will be contingent on the emission of the response within the specified interval; in Phase 2, light will be added four times during each session, for 1 min each; in Phase 3, the light will be followed by the delivery of an uncontrollable 0.8 mA/0.5 s shock; in Phase 4, the light will be presented without the shock following. Precision (percentage of responses that meet the reinforcement criterion) and response rate will be measured. Comparisons of these records in the presence and absence of light, before and during its pairing with shocks (Phases 1 to 3) and in extinction (Phase 4), will be performed. The effects on precision will be compared to the effect on rates, allowing for a more comprehensive analysis of conditioned suppression.