Can we reliably measure cognitive effort? On the relation of implicit and explicit cognitive effort scales and tasks.

Abstract

We tend to choose the action that is least demanding however measuring individual differences in the cost of cognitive effort can be elusive. We here report a set of five studies studying the relationship between four cognitive effort measures: the demand selection task, the cognitive effort discounting paradigm, a rationality battery to assess deliberate reasoning, and the Need for Cognition scale. We also measured working memory capacity in four studies. Subjective effort with the NASA task load index was measured in three studies. Need for Cognition was positively associated with effort spent in the cognitive effort discounting paradigm, and was also positively associated with deliberate reasoning, but there was no association with demand avoidance in the demand selection task. Working memory capacity was not related to Need for Cognition, demand avoidance or cognitive effort discounting but to deliberate reasoning. We conclude that the tasks may not measure the same latent cognitive effort construct. We discuss task-sensitivity in measuring cognitive effort, and the necessity to control for cognitive abilities.