Ontogeny of passive avoidance learning in domestic chicks: punishment of key-peck and running responses

Area of Science:

• Behavioral Neuroscience
• Developmental Psychology
• Animal Learning

Background:

• Passive avoidance (PA) learning demonstrates age-dependent changes in young chicks.
• Previous research suggests developmental changes in inhibitory ability influence chick learning.

Purpose of the Study:

• To investigate the effect of prepunishment acquisition trials on age-dependent passive avoidance learning in Vantress X Arbor Acre chicks.
• To determine if acquisition trial numbers modulate the learning differences between 1-day-old and 4-day-old chicks.

Main Methods:

• Chicks (1- and 4-day-old) underwent initial training for heat reward.
• Responses were subsequently punished with wing shocks after a variable number of reinforced acquisition trials.
• Passive avoidance learning was assessed using key-peck and runway tests across nine experiments.

Main Results:

• The number of reinforced acquisition trials significantly influenced the age dependency of passive avoidance learning.
• 1-day-old chicks learned as effectively as 4-day-old chicks when provided with numerous prepunishment acquisition trials.
• Fewer acquisition trials resulted in significantly less response suppression in 1-day-old chicks compared to 4-day-old chicks.

Conclusions:

• Age-dependent changes in passive avoidance learning are specifically related to the number of reinforced training trials.
• Developmental changes in general inhibitory ability do not solely explain age-related learning differences.
• 1-day-old chicks may be deficient in learning or detecting stimulus- and/or response-reinforcement contingencies compared to 4-day-old chicks.