In the target article, Kurzban et al. attempt to explain phenomena such as mental effort, fatigue, and boredom. They derive these phenomena from the functioning of a hypothetical mechanism which mechanically estimates the utilities of different possible actions and then selects the action that has a maximal expected utility. The idea seems interesting but its implementation in the article has fundamental problems. The article contains no formal description of possible actions. Kurzban et al. arbitrarily select possible actions for each situation considered in the article. However, such an approach is wrong, because the number of possible actions is potentially infinite in any situation (Russell & Norvig Reference Russell and Norvig2003). Because possible actions can be very different, the unconscious comparison of their utilities seems impossible. Kurzban et al. do not explain how the mind compares doing math calculations and mind wandering. The functioning of the hypothetical mechanism is described abstractly without pointing to the situations in which mental effort and boredom occur (see the target article's Figure 1). As a result, it is unclear why the output of this mechanism is mental effort and fatigue rather than, for example, fear and anxiety. Fear and anxiety can obviously be applied to optimize costs and benefits.
Another model can be sketched as an alternative to the authors' approach and the theories of depleting resources. Some details should be specified prior to the description of the model. Mental effort and fatigue occur in two sorts of situations. First, mental effort and fatigue usually occur when an individual attempts to acquire novel skills. However, this activity is typically not perceived as boring and negative. As an individual acquires a novel skill, the feeling of mental effort usually disappears (Logan Reference Logan1985). It is reasonable to assume that in this case mental effort simply reflects the necessary restructuring of the mind. Second, mental effort and fatigue frequently occur when the mental activity of an individual is not difficult but is long-term. In this case, mental effort is perceived as aversive. Obviously, the experiments in the target article were simple but long-term mental activities. The proposed model deals with such situations.
The proposed alternative model is based on two assumptions. First, the mind is able to maintain several processes in parallel. One of the processes is a task which occupies the focus of consciousness while other processes function in a background mode. Second, pursuing a long-term goal is usually an execution of a limited number of actions; many of them should be performed over and over again. As a result, any long-term activity is a sequence of recurring actions and therefore it is monotonous.
The brain has two systems that process monotony and its antagonist, novelty. One system is associated with the hippocampus (Grossberg & Merrill Reference Grossberg and Merrill1992; Vinogradova Reference Vinogradova2001). This system has a representation of the ongoing situation and compares it with the input from other brain systems. A mismatch between the representation and the input means that the situation is changed, and then the brain is activated. If the representation matches the input, then habituation occurs and the brain activity is decreased (Vinogradova Reference Vinogradova2001). The second system is the novelty-seeking system, which is responsible for seeking novel and varied sensations and experiences (Roberti Reference Roberti2004; Zuckerman Reference Zuckerman1994). The functioning of this system is associated with the interaction between neurotransmitter systems that are concentrated in the limbic areas of the brain (Zuckerman Reference Zuckerman1996).
It can be hypothesized that the monotony of long-term activities leads to the engagement of both novelty-processing systems. The first system attempts to inhibit the ongoing task, and the second system tries to activate any parallel processes. The feeling of mental effort reflects the competition between the task, which suffers from inhibition, and other processes. Fatigue and boredom mirror the inhibition of the ongoing task and habituation. The reduction of performance in tasks such as vigilance tasks results from the inhibition of the task by the first system. Accordingly, changes in the situation may result in the improvement of performance owing to the activation of the brain by this system. The decrement in performance when participants perform sequentially several tasks can be explained on the basis that these tasks share the common experimental context (one experimenter, one room, etc.), and therefore the situation can be considered monotonous.
The relationship between reward and fatigue can be hypothesized as a consequence of the interaction between the novelty-processing systems and the reward system. Indeed, novelty seeking should be maximally intense in neutral situations, because seeking novel sensations in very dangerous or very pleasant situations is hardly a useful strategy. As a result, reward can inhibit the novelty-processing systems, thereby decreasing the feeling of fatigue.
The feelings of fatigue and boredom in long-term activities possibly reflect a conflict between various brain systems. In my opinion, the ability to pursue long-term goals having no innate basis is the main characteristic distinguishing humans from other animals (Prudkov Reference Prudkov1999; Reference Prudkov2005). The experiments described in the target article are obvious examples of pursuing such goals. Indeed, subjects participated in the vigilance tasks not because they were hungry, sexually unsatisfied, or frightened. The ability is maintained by the prefrontal lobes (Luria Reference Luria1966; Reference Luria, Luria and Homskaya1982). This is a young structure maximally advanced in humans (Luria Reference Luria1966).
However, long-term activities often are monotonous. Monotony results in the activation of the novelty-processing systems. These systems are maintained by ancient limbic structures, which also maintain other biological goals (Kolb & Whishaw Reference Kolb and Whishaw2003). For the novelty-processing systems, pursuing social goals is a neutral situation because the limbic structures are weakly involved in processing social goals. Therefore, in this case the novelty-processing systems should be activated, thereby hindering social activities.
Kurzban et al. ask, “Why, if revising a manuscript contributes to the achievement of key long-term goals, does it feel aversively ‘effortful’?” (sect. 2.1, para. 4). They attempt to respond to this question, but the target article does not contain a clear answer. The proposed model, however, offers a simple solution: because a mature scientist frequently revises manuscripts and this activity becomes monotonous.
In the target article, Kurzban et al. attempt to explain phenomena such as mental effort, fatigue, and boredom. They derive these phenomena from the functioning of a hypothetical mechanism which mechanically estimates the utilities of different possible actions and then selects the action that has a maximal expected utility. The idea seems interesting but its implementation in the article has fundamental problems. The article contains no formal description of possible actions. Kurzban et al. arbitrarily select possible actions for each situation considered in the article. However, such an approach is wrong, because the number of possible actions is potentially infinite in any situation (Russell & Norvig Reference Russell and Norvig2003). Because possible actions can be very different, the unconscious comparison of their utilities seems impossible. Kurzban et al. do not explain how the mind compares doing math calculations and mind wandering. The functioning of the hypothetical mechanism is described abstractly without pointing to the situations in which mental effort and boredom occur (see the target article's Figure 1). As a result, it is unclear why the output of this mechanism is mental effort and fatigue rather than, for example, fear and anxiety. Fear and anxiety can obviously be applied to optimize costs and benefits.
Another model can be sketched as an alternative to the authors' approach and the theories of depleting resources. Some details should be specified prior to the description of the model. Mental effort and fatigue occur in two sorts of situations. First, mental effort and fatigue usually occur when an individual attempts to acquire novel skills. However, this activity is typically not perceived as boring and negative. As an individual acquires a novel skill, the feeling of mental effort usually disappears (Logan Reference Logan1985). It is reasonable to assume that in this case mental effort simply reflects the necessary restructuring of the mind. Second, mental effort and fatigue frequently occur when the mental activity of an individual is not difficult but is long-term. In this case, mental effort is perceived as aversive. Obviously, the experiments in the target article were simple but long-term mental activities. The proposed model deals with such situations.
The proposed alternative model is based on two assumptions. First, the mind is able to maintain several processes in parallel. One of the processes is a task which occupies the focus of consciousness while other processes function in a background mode. Second, pursuing a long-term goal is usually an execution of a limited number of actions; many of them should be performed over and over again. As a result, any long-term activity is a sequence of recurring actions and therefore it is monotonous.
The brain has two systems that process monotony and its antagonist, novelty. One system is associated with the hippocampus (Grossberg & Merrill Reference Grossberg and Merrill1992; Vinogradova Reference Vinogradova2001). This system has a representation of the ongoing situation and compares it with the input from other brain systems. A mismatch between the representation and the input means that the situation is changed, and then the brain is activated. If the representation matches the input, then habituation occurs and the brain activity is decreased (Vinogradova Reference Vinogradova2001). The second system is the novelty-seeking system, which is responsible for seeking novel and varied sensations and experiences (Roberti Reference Roberti2004; Zuckerman Reference Zuckerman1994). The functioning of this system is associated with the interaction between neurotransmitter systems that are concentrated in the limbic areas of the brain (Zuckerman Reference Zuckerman1996).
It can be hypothesized that the monotony of long-term activities leads to the engagement of both novelty-processing systems. The first system attempts to inhibit the ongoing task, and the second system tries to activate any parallel processes. The feeling of mental effort reflects the competition between the task, which suffers from inhibition, and other processes. Fatigue and boredom mirror the inhibition of the ongoing task and habituation. The reduction of performance in tasks such as vigilance tasks results from the inhibition of the task by the first system. Accordingly, changes in the situation may result in the improvement of performance owing to the activation of the brain by this system. The decrement in performance when participants perform sequentially several tasks can be explained on the basis that these tasks share the common experimental context (one experimenter, one room, etc.), and therefore the situation can be considered monotonous.
The relationship between reward and fatigue can be hypothesized as a consequence of the interaction between the novelty-processing systems and the reward system. Indeed, novelty seeking should be maximally intense in neutral situations, because seeking novel sensations in very dangerous or very pleasant situations is hardly a useful strategy. As a result, reward can inhibit the novelty-processing systems, thereby decreasing the feeling of fatigue.
The feelings of fatigue and boredom in long-term activities possibly reflect a conflict between various brain systems. In my opinion, the ability to pursue long-term goals having no innate basis is the main characteristic distinguishing humans from other animals (Prudkov Reference Prudkov1999; Reference Prudkov2005). The experiments described in the target article are obvious examples of pursuing such goals. Indeed, subjects participated in the vigilance tasks not because they were hungry, sexually unsatisfied, or frightened. The ability is maintained by the prefrontal lobes (Luria Reference Luria1966; Reference Luria, Luria and Homskaya1982). This is a young structure maximally advanced in humans (Luria Reference Luria1966).
However, long-term activities often are monotonous. Monotony results in the activation of the novelty-processing systems. These systems are maintained by ancient limbic structures, which also maintain other biological goals (Kolb & Whishaw Reference Kolb and Whishaw2003). For the novelty-processing systems, pursuing social goals is a neutral situation because the limbic structures are weakly involved in processing social goals. Therefore, in this case the novelty-processing systems should be activated, thereby hindering social activities.
Kurzban et al. ask, “Why, if revising a manuscript contributes to the achievement of key long-term goals, does it feel aversively ‘effortful’?” (sect. 2.1, para. 4). They attempt to respond to this question, but the target article does not contain a clear answer. The proposed model, however, offers a simple solution: because a mature scientist frequently revises manuscripts and this activity becomes monotonous.