Methodological issues with value-based decision-making (VBDM) tasks: The effect of trial wording on evidence accumulation outputs from the EZ drift-diffusion model

Most value-based decision-making (VBDM) tasks instruct people to make value judgements about stimuli using wording relating to consumption, however in some contexts this may be inappropriate. This study aims to explore whether variations of trial wording capture a common construct of value. This is a pre-registered experimental study with a within-subject design. Fifty-nine participants completed a two-alternative forced-choice task where they chose between two food images. Participants completed three blocks of trials: one asked which they would rather consume (standard wording), one asked which image they liked more, and one asked them to recall which image they rated higher during a previous block. We fitted the EZ drift-diffusion model to the reaction time and choice data to estimate evidence accumulation (EA) processes during the different blocks. There was a highly significant main effect of trial difficulty, but this was not modified by trial wording (F = 2.00, p = .11, ηp2 = .03, BF10 = .05). We also found highly significant positive correlations between the EA rates across task blocks (rs > .44, ps < .001). The findings provide initial validation of alternative wording in VBDM tasks that can be used in contexts where it may be undesirable to ask participants to make consummatory judgements.