Negative emotions such as stress and anxiety can have an effect on cognitive processes, with many studies showing that inducing negative mood states in individuals leads to a reduction in executive functions (Grant et al, 2001; Hammar & Ardal, 2009).
This reduction may be caused by a depletion in limited attention resources in individuals experiencing negative mood states (Ellis & Ashbrook, 1988). Attention—the cognitive process that selects stimuli for further processing—is fundamental to distinguish information that signals a potential threat or reward in mentally healthy individuals (Anderson, 2013), but anxious individuals show attentional bias towards threat (Williams et al., 1996) which can manifest itself through several cognitive mechanisms.
First, the literature has shown that attention can be systematically biased towards negative stimuli when individuals are experiencing negative mood states (Beck, 1967), with both trait anxious and clinically anxious individuals devoting their attention towards threatening sources of information, at the expense of other activities (Bar-Haim et al, 2007). Attentional bias has been repeatedly observed and measured using the dot probe task (MacLeod et al., 1986), in which a participant is presented with two stimuli (usually words or images) on each sides of a screen, then with a probe in a location previously occupied by one of the stimuli.
The individual presses a button to indicate the location of the probe. Researchers can measure attentional biases using the different response times towards congruent trials (probe replacing threatening stimulus) and incongruent trials (probe replacing neutral stimulus). This behaviour can become maladaptive and cause unnecessary distress: while low anxiety individuals only show attentional biases towards severely threatening situations, high anxiety individuals show attentional biases towards both moderately and severely threatening stimuli (Wilson and MacLeod, 2003).
A second mechanism where stress and anxiety have a potential impact on attention is the difficulty in disengaging attention from threat stimuli. Delayed disengagement has been studied using several methodologies, including the spatial cueing task (Posner, 1980), where a participant is asked to fixate a point between two stimuli. They are then presented with a cue, followed by a target appearing inside one of the stimuli, and asked to press a key indicating the stimuli in which the target is located.
Attentional biases are measured by the difference in response times between valid threat-cued, invalid threat-cued, and neutral-cued trials. Researchers have found delayed disengagement to be more present amongst anxious individuals (Fox et. al, 2001; 2002, experiment 1), with threatening stimuli not only capturing but holding the attention of anxious individuals (Koster et al., 2004).
Lastly, attentional avoidance is a behaviour where individuals allocate their attention towards a location opposite the location of the threatening stimuli, and has mainly been observed when the threat is present for a longer period of time (Koster et al., 2005). Faced with a threatening stimulus, individuals with an anxiety disorder such as phobia will typically display facilitated attention by fixating the stimulus at first, then attentional avoidance by moving their eyes away from the stimulus (Pflugshaupt et al., 2005).
These manifestation of attentional biases can contribute to the maintenance or onset of psychological disorders: a large study conducted recently with 1,291 participants showed an association between attention bias to threat and some anxiety symptoms such as social anxiety in children and adolescents (Abend et al., 2018).
Attentional control, the cognitive ability to regulate attentional allocation, has been studied as a potential mediating mechanism to anxiety. While it is possible to mitigate attention biases to a certain extent, it is particularly difficult for individuals with high anxiety to compensate for poor attentional control: the attentional control theory posits that anxiety increases bottom-up stimulus-driven processing which shifts attention from one task to another and impairs top-down regulatory control which inhibits automatic responses, facilitating the detection of and delaying the disengagement from threatening stimuli in anxious individuals (Eysenck, 2007).
This theory as well as the strong connexion between attentional biases and anxiety found in the existing literature have inspired researchers to explore Attention Bias Modification Treatment—a novel therapeutic approach targeting specific attentional biases—as a potential treatment for anxiety. A meta-analysis concluded that ABMT shows promise, with significantly greater reductions in anxiety than control (Hakamata et al., 2010), but more randomised controlled trials are needed to measure its therapeutic effects.
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