What predicts cognitive effort? : optimality, preferences, and strategies

Daily life is filled with complex tasks we must navigate that require varying levels of cognitive control. Whether we are writing up a report or playing a chess game, we must work to meet effort demands, obtain rewards, and avoid losses. The deployment of cognitive control, through cognitive effort, is guided by a combination of factors including the capacity to deploy effort and trait-level factors including depression and chronic stress. These factors are critical to efficient everyday decision making, as they could inform optimal effort choices associated with desirable outcomes or suboptimal choices associated with undesirable outcomes. However, past work has not identified whether these factors predict differences in choices about how much cognitive effort to deploy given changes in effort demands and potential outcomes. In my dissertation, I propose a novel theoretical framework that characterizes trait-level dispositions and state-level factors that predict reward evaluation, effort costs, and overall patterns of choice behaviours in cognitive effort. I validate this framework through a series of human choice tasks engaging visual short-term memory demands with translational relevance to previous effort work in rodents. Specifically, I evaluate whether visual short-term memory ability, individual differences in depression and chronic stress levels, and everyday preferences for engaging in effortful tasks predict preferences for more vs. less challenging tasks when effort demands are either static (Chapters 2-3) or shifting (Chapters 4-5). Throughout, I show that cognitive capacity was a key predictor of preferences for high-effort, high-reward options. When effort demands and available rewards shifted, lower chronic stress levels and stronger preferences for attentional control - together with higher visual short-term memory ability - predicted more choices to encode larger sets of shapes for higher rewards (Chapter 4). Furthermore, higher depression levels were associated with impairments in high effort choices given the possibility of loss outcomes (Chapter 5). Throughout, I highlight the context dependence of the choices that humans make about cognitive effort deployment through simple and challenging paradigms alike.