Authors: Erik Bijleveld, Roshan Cools
Affiliation(s): Radboud University/Radboudumc
Keywords: decision-making, foraging, stress, depression, anxiety, ADHD
Research question(s):
- How reliable are virtual patch foraging task measures?
- Is variation in foraging behavior across sessions associated with variation in chronic and acute stress levels, and does this variation differ under high allostatic load?
- Is variation in foraging behavior across sessions associated with variation self-reported depression and anxiety?
- Are average foraging strategies across sessions related to self-reported ADHD phenotypes?
Link: OSF preregistration
Abstract:
In ecological contexts, foraging-style tasks study how organisms optimize some fitness objective (e.g. maximizing reward rate), while balancing rewards and costs. When foraging in a patchy environment (e.g., a field of berry bushes), decisions involve a tradeoff between harvesting rewards available from the current (depleting) patch, and the time spent traveling to a different (but richer) one. The level at which the forager decides to exit the current patch (i.e., their ‘exit threshold’ or the reward they expected to receive when they decided to leave) reveals the point of equivalence in this tradeoff. This is formalized in Marginal Value Theorem (Charnov et al. 1976), which asserts that a simple threshold policy maximizes reward rate; the forager simply needs to maintain an estimate of the average reward rate in the environment and exit a patch when the instantaneous reward rate falls below the average. Humans demonstrate behavior consistent with the MVT and individual differences in patch foraging exit thresholds have been associated with acute and chronic stress, severity of major depressive disorder symptoms, and self-reported ADHD phenotypes. However, this research has largely been cross-sectional and involved smaller sample sizes. Moreover, there is a gap in understanding the psychometric properties of these patch foraging tasks. We propose to leverage the HBS i) to estimate test-retest reliability of exit thresholds, and ii) to test whether exit thresholds are related to acute and chronic stress, proxies of allostatic load, and self-reported mental health (depression, anxiety, ADHD, and impulsivity). These analyses will replicate previously findings, and extend these to investigate the stable versus dynamic component of exit thresholds longitudinally. The insights from our proposed project will be important for the growing community of researchers who use foraging models, but also for the broader community of researchers interested in the association between stress and goal-directed behavior.