Increasing motivation in effort-based decision-making tasks: effects of salience and reward expectancy manipulations.

Background: A significant proportion of patients with affective and psychotic disorders show a marked reduction in goal-directed behaviour, which is also reflected in the behavioural outcomes of effort-based decision-making paradigms. The factors underlying this reduction are not yet fully understood. Reward salience and reward expectancy have been discussed as factors that potentially influence approach behaviour. The aim of this study was thus to test their effects on behaviour in an effort-based decision-making paradigm.

Methods: In two studies with community samples we applied a modified version of the Balloon Task. In study 1, we manipulated reward salience in a within-subject design (N = 32) by highlighting the monetary rewards. In study 2, we manipulated reward expectancy in a between-subject design (N = 72) by adding five practice trials with either positive or negative feedback prior to the task.

Results: The salience of rewards manipulation significantly increased effort expenditure and the allocation of effort to the level of rewards whereas the reward expectancy manipulation did not.

Conclusions: The finding that increasing the salience of rewards increases motivated behaviour in an effort-based decision-making paradigm offers promising possibilities for intervention in disorders characterised by motivational deficits, such asaffective and psychotic disorders.