Riding the elephant in the room: Towards a revival of the optimal level of stimulation model

Phenomena such as engagement, attention and curiosity rely heavily on the “optimal-level of stimulation (or arousal)” model, which suggests they are driven by stimuli being neither too simple nor too complex. Two points often overlooked in psychology are that each stimulus is simultaneously processed with its context, and that a stimulus complexity is relative to an individual’s cognitive resources to process it. According to the “optimal-level of stimulation” model, while familiar contexts may decrease the overall stimulation and favour exploration of novelty, a novel context may increase the overall stimulation and favour preference for familiarity. In order to stay closer to their optimum when stimulation is getting too high or too low, individuals can explore other stimuli, adopt a different processing style or be creative. The need and the ability to adopt such strategies will depend upon the cognitive resources available, which can be affected by contextual stimulation and by other factors such as age, mood or arousability. Drawing on empirical research in cognitive and developmental psychology, we provide here an updated “optimal-level of stimulation” model, which is holistic and coherent with previous literature. Once taken into account the role of contextual stimulation as well as the diverse factors influencing internal cognitive resources, such model fits with and enriches other existing theories related to exploratory behaviors. By doing so, it provides a useful framework to investigate proximate explanations underlying learning and cognitive development, and to develop future interventions related, for example, to eating, and learning disorders.