What Is the Subjective Cost of Cognitive Effort? Load, Trait, and Aging Effects Revealed by Economic Preference

Andrew Westbrook,Todd S Braver,Daria Kester,Mathias Pessiglione

doi:10.1371/journal.pone.0068210

Andrew Westbrook, Todd S Braver + Show 2 more

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https://doi.org/10.1371/journal.pone.0068210

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Journal: PloS one	Publication Date: Jul 22, 2013
Citations: 363	License type: CC BY 4.0

Affiliation: Washington University in St. Louis

Abstract

It has long been assumed that people treat cognitive effort as costly, but also that such effort costs may vary greatly across individuals. Individual differences in subjective effort could present a major and pervasive confound in behavioral and neuroscience assessments, by conflating cognitive ability with cognitive motivation. Self-report cognitive effort scales have been developed, but objective measures are lacking. In this study, we use the behavioral economic approach of revealed preferences to quantify subjective effort. Specifically, we adapted a well-established discounting paradigm to measure the extent to which cognitive effort causes participants to discount monetary rewards. The resulting metrics are sensitive to both within-individual factors, including objective load and reward amount, and between-individual factors, including age and trait cognitive engagement. We further validate cognitive effort discounting by benchmarking it against well-established measures of delay discounting. The results highlight the promise and utility of behavioral economic tools for assessing trait and state influences on cognitive motivation.

Highlights

Is cognitive effort costly? There is a long tradition within psychology of characterizing humans as ‘‘cognitive misers’’ [1], who conserve cognitive effort, all else being equal ([2,3], [4] on general effort avoidance)
In Experiment 2, reliable linear contrasts obtained for YA, for both the $1 offers (N = 2–4, F1,49 = 13, P,0.01, g2 = 0.21) and $5 offers (F1,49 = 15, P,0.01, g2 = 0.24), and for OA, for both the $1 offers (N = 2– 4, F1,46 = 13, P,0.01, g2 = 0.22) and $5 offers (N = 2–4, F1,46 = 16, P,0.01, g2 = 0.26), indicating that effort costs increased with objective load
Our analysis is based on proportional comparisons between amounts not because we assume any particular effort discounting function, but because discounting was clearly not subtractive

Summary

Introduction

There is a long tradition within psychology of characterizing humans as ‘‘cognitive misers’’ [1], who conserve cognitive effort, all else being equal ([2,3], [4] on general effort avoidance). This implies that individuals value their effort, treating it as costly. Variability in behavioral and neural measurements during task performance may reflect cognitive motivation as well as cognitive ability This may be relevant for understanding apparent cognitive deficits observed in clinical populations featuring anergia or avolition [7,8,9,10], or among older adults [11,12]

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