This coactivation will have two potentially adverse consequences for behavior. At best it will slow responding, since the correct response unit must overcome inhibitory competition from the incorrect one. At worst it will produce an error. These dangers can be ameliorated by increasing the activity of the color naming task unit. Thus, conflict serves as an indicator of the need for additional allocation of control. This simple model of the Stroop task and conflict monitoring is of course not intended as a comprehensive Bortezomib model of cognitive control. However, the architecture of the model illustrates three core component functions of cognitive

control (Figure 2A). Regulation. The sine qua non feature of control is its capacity to govern or influence lower level information-processing mechanisms, a function we refer to as regulation. In the language of engineering, activity of a task unit represents a control Selleckchem VX-770 signal, which determines the parameters for more basic processes (in this case, the sensitivity of the associative units in the corresponding pathway). Note that this signal has two defining characteristics:

its identity and its intensity (the strength of the signal, both in literal terms—e.g., level of activation of the task unit—and in terms of its impact on information processing). Control signals can determine a wide range of processing parameters, including thresholds and/or biases for responding (governing speed-accuracy tradeoffs; Bogacz et al., 2006 and Wiecki and Frank, 2013), templates

for attention or memory search ( Desimone and Duncan, 1995, Olivers et al., 2011 and Polyn et al., 2009), and modulators of emotion ( Johns et al., 2008 and McClure et al., 2006). In each case, a distinction can be made between signal identity (the parameter targeted) and signal intensity (the degree to which the parameter is displaced from its default value). Specification. In order for regulation to occur, a critical step is for an appropriate control signal to be chosen: Control requires a decision on which, if any, controlled task(s) should be undertaken, and on how intensively it (or they) should be pursued. We refer to this decision-making function as control signal specification, which must determine Ketanserin the identity and intensity of the desired control signal(s). In principle, it is possible to specify more than one identity-intensity pairing, and thereby more than one task (see Figure 2). However, in practice there are strict capacity constraints on control, and thus in this Review we focus on the simplest and most common circumstance, involving specification of a single identity-intensity pairing (i.e., a single control demanding task). Importantly, control signal specification should be distinguished from regulation which consists of implementing the specified control signal so as to actually effect the changes in information processing required for the task.