Goal-direction and habit in human and nonhuman behavioral sequences (behavior chains)

Area of Science:

• Behavioral neuroscience
• Cognitive psychology

Background:

• Habits play a crucial role in daily life and are implicated in behavioral pathologies like addiction.
• Research in rats suggests habit formation, characterized by outcome-insensitivity, develops with extensive practice.

Purpose of the Study:

• To investigate habit formation in humans using a two-response discriminated behavior chain.
• To determine if extended training reduces sensitivity of the first response (R1) to the extinction of the second response (R2).

Main Methods:

• Rats and human participants learned two-response chains (R1-R2) where both responses were needed for reinforcement.
• R1's sensitivity to R2 extinction was assessed after moderate and extended training.
• Experiment 3 specifically trained humans on a single R1-R2 chain before R2 extinction.

Main Results:

• In rats, R1 was sensitive to R2 extinction after moderate but not extended training, indicating habit.
• In humans, extended training on multiple chains did not reduce R1 sensitivity to R2 extinction.
• However, with a single chain and extended training, human R1 became insensitive to R2 extinction, suggesting habit formation.

Conclusions:

• Habit formation, characterized by response insensitivity to outcome changes, can be demonstrated in humans under specific laboratory conditions.
• Findings align with nonhuman research but highlight challenges in demonstrating human habits.
• This research contributes to understanding the mechanisms underlying habit formation and its potential role in addiction.