Effects of task complexity and working memory load on eye-tracking indices of cognitive effort in adults and children
Cognitive effort a subjective phenomenon, generally defined as the amount of sustained mental activity, exerted during a cognitive task. A well-established eye movement indice of cognitive effort is blink rate. Many studies show that in cognitive tasks that involve visual stimuli blink rate decreases as a function of difficulty (Maffei, & Angrilli, 2018). Working memory (WM) is a core cognitive ability and refers to the number of items or schemes that can be simultaneously held and manipulated in mind. While a great deal of studies have explored behavioral correlates of WM load and task complexity, little is known about how these relate to eye movements across development. We implement an eye-tracking paradigm to study effect of complexity and WM load on eye movements from a developmental perspective. 57 healthy adults (23 male., age = 23.25±3.6) and 26 children (10 male, age = 9.53±0.76) participated in the study. Eye-tracking data was recorded with the EyeLink Portable Duo, while participants performed the Colour Matching Task (Arsalidou et al., 2010). During the CMT the participant is shown a picture with multiple colours for 3 s. and gives a response at the following picture: are the colours same or different. CMT has 6 levels of WM load: the number of relevant colors and two levels of task complexity (low and high interference conditions). Analyses of variance showed a significant main effect of age group on blink rate (p < 0.01, F = 9.091, η2 = 0.009) with children making less blinks in all levels of WM load, as well as significant main effect of WM load (p < 0.001, F = 130.5, η2 = 0.021) with blink rate decreasing as WM load increased. No significant effects were observed for task complexity. Results will be discussed in terms of cognitive development and implications to education.