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A simple hypothesis of executive function.

Kopp B - Front Hum Neurosci (2012)

Bottom Line: Executive function is traditionally conceptualized as a set of abilities required to guide behavior toward goals.Here, an integrated theoretical framework for executive function is developed which has its roots in the notion of hierarchical mental models.Further following Duncan (2010a,b), executive function is construed as a hierarchical recursive system of test-operation-test-exit units (Miller et al., 1960).

View Article: PubMed Central - PubMed

Affiliation: Cognitive Neurology, Technische Universität Braunschweig, Department of Neurology Braunschweig Hospital, Germany.

ABSTRACT
Executive function is traditionally conceptualized as a set of abilities required to guide behavior toward goals. Here, an integrated theoretical framework for executive function is developed which has its roots in the notion of hierarchical mental models. Further following Duncan (2010a,b), executive function is construed as a hierarchical recursive system of test-operation-test-exit units (Miller et al., 1960). Importantly, it is shown that this framework can be used to model the main regional prefrontal syndromes, which are characterized by apathetic, disinhibited and dysexecutive cognition, and behavior, respectively. Implications of these considerations for the neuropsychological assessment of executive function are discussed.

No MeSH data available.


Related in: MedlinePlus

Illustration of a recursive mental TOTE model capable of controlling intentional behavior (just two levels are drawn for illustration). TOTE units are self-terminating operating units, each capable of activating otherwise comparable units at sub-ordinate levels of the hierarchical structure (top-down arrows). The exit-operator of the active TOTE unit passes control of operations to the super-ordinate TOTE unit (bottom-up arrows), once the self-terminating condition is reached. Each TOTE unit is comprises three operators (T, test; O, operation; E, exit). Activated test-operation-retest loops are running until the actual state matches the goal state. The exit-operator is executed (i.e., E()) whenever the self-terminating condition is reached (i.e., Δ = 0), so that control of operations is passed to the super-ordinate unit. Only TOTE units at the lowest level of the hierarchical structure are capable of activating executable behavioral units, whereas units at the hyper-planes are solely capable of activating units at sub-ordinate levels of the hierarchical structure. In this example, a hyper-unit, labeled τ, activates a unit at the lowest level of the hierarchical structure, labeled θ1, which in turn activates executable behavioral units (solid arrows). In contrast, the connections between the un-activated unit θ2 at the lowest level and executable behavioral units are not active (dashed arrows). Switching activation states requires executing the exit-operator of unit θ1, once its self-terminating condition has been reached, i.e., E(θ1) if Δθ1 = 0, and the activation of unit θ2 by the hyper-unit τ. By way of this analysis, the current hypothesis of executive function offers a framework for understanding the effects of prefrontal lesions on behavioral performance in task switching paradigms (Robbins, 2007; Shallice et al., 2008; Nyhus and Barceló, 2009; Kopp and Wessel, 2011).
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Figure 2: Illustration of a recursive mental TOTE model capable of controlling intentional behavior (just two levels are drawn for illustration). TOTE units are self-terminating operating units, each capable of activating otherwise comparable units at sub-ordinate levels of the hierarchical structure (top-down arrows). The exit-operator of the active TOTE unit passes control of operations to the super-ordinate TOTE unit (bottom-up arrows), once the self-terminating condition is reached. Each TOTE unit is comprises three operators (T, test; O, operation; E, exit). Activated test-operation-retest loops are running until the actual state matches the goal state. The exit-operator is executed (i.e., E()) whenever the self-terminating condition is reached (i.e., Δ = 0), so that control of operations is passed to the super-ordinate unit. Only TOTE units at the lowest level of the hierarchical structure are capable of activating executable behavioral units, whereas units at the hyper-planes are solely capable of activating units at sub-ordinate levels of the hierarchical structure. In this example, a hyper-unit, labeled τ, activates a unit at the lowest level of the hierarchical structure, labeled θ1, which in turn activates executable behavioral units (solid arrows). In contrast, the connections between the un-activated unit θ2 at the lowest level and executable behavioral units are not active (dashed arrows). Switching activation states requires executing the exit-operator of unit θ1, once its self-terminating condition has been reached, i.e., E(θ1) if Δθ1 = 0, and the activation of unit θ2 by the hyper-unit τ. By way of this analysis, the current hypothesis of executive function offers a framework for understanding the effects of prefrontal lesions on behavioral performance in task switching paradigms (Robbins, 2007; Shallice et al., 2008; Nyhus and Barceló, 2009; Kopp and Wessel, 2011).

Mentions: Lashley (1951) had argued long ago that behavior is hierarchically structured, and Miller et al. (1960) introduced the “test-operate-test-exit” (TOTE) unit to cognitive psychology just a few years later. When selected, a TOTE unit would test a particular environmental state and, if a specified condition was not met, would execute a specific operation until the condition became true. Miller et al. (1960) suggested that all kinds of behavior are controlled by TOTE units and used the everyday example of hammering a nail. The unit consists of a test-operator [Is the nail down? (Is the goal state achieved?)], an operation [hammering (and return to test)], and an exit-operator [to be executed if the goal state has been achieved (see test-operator)]. Crucially, the operation of a TOTE unit could be to select another TOTE unit, allowing for hierarchical structuring based on recursive processing (Corballis, 2011), i.e., by running a series of nested TOTE units. Details of the idea of recursive activation of self-terminating operating units are illustrated in Figure 2. Inspection of Figure 2 reveals that mental models may be considered as hierarchical structures of self-terminating operating units, each capable of activating otherwise comparable units at sub-ordinate levels of the hierarchical structure (Botvinick, 2008; Duncan, 2010a,b). Notice that the multiple-demand system framework (Duncan, 2010a,b) provides partly similar accounts of the crucial features of internal models guiding sequential behavior in complex situations. Specifically, both views share the idea of hierarchically organized internal models (see also Miller et al., 1960). The view which is presented here is oriented toward the manifold behavioral disturbances which usually follow frontal lobe lesions and which were shortly foreshadowed above, whereas Duncan's model (Duncan, 2010a,b) is focused more on the neurocognitive mechanisms of complex problem solving and (fluid) intelligence.


A simple hypothesis of executive function.

Kopp B - Front Hum Neurosci (2012)

Illustration of a recursive mental TOTE model capable of controlling intentional behavior (just two levels are drawn for illustration). TOTE units are self-terminating operating units, each capable of activating otherwise comparable units at sub-ordinate levels of the hierarchical structure (top-down arrows). The exit-operator of the active TOTE unit passes control of operations to the super-ordinate TOTE unit (bottom-up arrows), once the self-terminating condition is reached. Each TOTE unit is comprises three operators (T, test; O, operation; E, exit). Activated test-operation-retest loops are running until the actual state matches the goal state. The exit-operator is executed (i.e., E()) whenever the self-terminating condition is reached (i.e., Δ = 0), so that control of operations is passed to the super-ordinate unit. Only TOTE units at the lowest level of the hierarchical structure are capable of activating executable behavioral units, whereas units at the hyper-planes are solely capable of activating units at sub-ordinate levels of the hierarchical structure. In this example, a hyper-unit, labeled τ, activates a unit at the lowest level of the hierarchical structure, labeled θ1, which in turn activates executable behavioral units (solid arrows). In contrast, the connections between the un-activated unit θ2 at the lowest level and executable behavioral units are not active (dashed arrows). Switching activation states requires executing the exit-operator of unit θ1, once its self-terminating condition has been reached, i.e., E(θ1) if Δθ1 = 0, and the activation of unit θ2 by the hyper-unit τ. By way of this analysis, the current hypothesis of executive function offers a framework for understanding the effects of prefrontal lesions on behavioral performance in task switching paradigms (Robbins, 2007; Shallice et al., 2008; Nyhus and Barceló, 2009; Kopp and Wessel, 2011).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 2: Illustration of a recursive mental TOTE model capable of controlling intentional behavior (just two levels are drawn for illustration). TOTE units are self-terminating operating units, each capable of activating otherwise comparable units at sub-ordinate levels of the hierarchical structure (top-down arrows). The exit-operator of the active TOTE unit passes control of operations to the super-ordinate TOTE unit (bottom-up arrows), once the self-terminating condition is reached. Each TOTE unit is comprises three operators (T, test; O, operation; E, exit). Activated test-operation-retest loops are running until the actual state matches the goal state. The exit-operator is executed (i.e., E()) whenever the self-terminating condition is reached (i.e., Δ = 0), so that control of operations is passed to the super-ordinate unit. Only TOTE units at the lowest level of the hierarchical structure are capable of activating executable behavioral units, whereas units at the hyper-planes are solely capable of activating units at sub-ordinate levels of the hierarchical structure. In this example, a hyper-unit, labeled τ, activates a unit at the lowest level of the hierarchical structure, labeled θ1, which in turn activates executable behavioral units (solid arrows). In contrast, the connections between the un-activated unit θ2 at the lowest level and executable behavioral units are not active (dashed arrows). Switching activation states requires executing the exit-operator of unit θ1, once its self-terminating condition has been reached, i.e., E(θ1) if Δθ1 = 0, and the activation of unit θ2 by the hyper-unit τ. By way of this analysis, the current hypothesis of executive function offers a framework for understanding the effects of prefrontal lesions on behavioral performance in task switching paradigms (Robbins, 2007; Shallice et al., 2008; Nyhus and Barceló, 2009; Kopp and Wessel, 2011).
Mentions: Lashley (1951) had argued long ago that behavior is hierarchically structured, and Miller et al. (1960) introduced the “test-operate-test-exit” (TOTE) unit to cognitive psychology just a few years later. When selected, a TOTE unit would test a particular environmental state and, if a specified condition was not met, would execute a specific operation until the condition became true. Miller et al. (1960) suggested that all kinds of behavior are controlled by TOTE units and used the everyday example of hammering a nail. The unit consists of a test-operator [Is the nail down? (Is the goal state achieved?)], an operation [hammering (and return to test)], and an exit-operator [to be executed if the goal state has been achieved (see test-operator)]. Crucially, the operation of a TOTE unit could be to select another TOTE unit, allowing for hierarchical structuring based on recursive processing (Corballis, 2011), i.e., by running a series of nested TOTE units. Details of the idea of recursive activation of self-terminating operating units are illustrated in Figure 2. Inspection of Figure 2 reveals that mental models may be considered as hierarchical structures of self-terminating operating units, each capable of activating otherwise comparable units at sub-ordinate levels of the hierarchical structure (Botvinick, 2008; Duncan, 2010a,b). Notice that the multiple-demand system framework (Duncan, 2010a,b) provides partly similar accounts of the crucial features of internal models guiding sequential behavior in complex situations. Specifically, both views share the idea of hierarchically organized internal models (see also Miller et al., 1960). The view which is presented here is oriented toward the manifold behavioral disturbances which usually follow frontal lobe lesions and which were shortly foreshadowed above, whereas Duncan's model (Duncan, 2010a,b) is focused more on the neurocognitive mechanisms of complex problem solving and (fluid) intelligence.

Bottom Line: Executive function is traditionally conceptualized as a set of abilities required to guide behavior toward goals.Here, an integrated theoretical framework for executive function is developed which has its roots in the notion of hierarchical mental models.Further following Duncan (2010a,b), executive function is construed as a hierarchical recursive system of test-operation-test-exit units (Miller et al., 1960).

View Article: PubMed Central - PubMed

Affiliation: Cognitive Neurology, Technische Universität Braunschweig, Department of Neurology Braunschweig Hospital, Germany.

ABSTRACT
Executive function is traditionally conceptualized as a set of abilities required to guide behavior toward goals. Here, an integrated theoretical framework for executive function is developed which has its roots in the notion of hierarchical mental models. Further following Duncan (2010a,b), executive function is construed as a hierarchical recursive system of test-operation-test-exit units (Miller et al., 1960). Importantly, it is shown that this framework can be used to model the main regional prefrontal syndromes, which are characterized by apathetic, disinhibited and dysexecutive cognition, and behavior, respectively. Implications of these considerations for the neuropsychological assessment of executive function are discussed.

No MeSH data available.


Related in: MedlinePlus