ANÁLISIS DEL SISTEMA Y PROYECCIONES

In a typical Stroop task (Stroop, 1935) that investigates selective attention, participants are asked to identify the ink colour of a letter string (typically, the name of a colour) whilst disregarding the meaning of the word. Participants demonstrate a reaction time latency when naming the ink colour of the written word. Literature has consistently shown that when the meaning of a word and its ink colour are congruent (e.g., green in green ink, red in red ink), response times are quicker than when the meaning of the word and its ink colours are incongruent (e.g., green in red ink, red in blue ink). Longer response latencies are attributed to colour-word interference (Stroop, 1935).

The Stroop task has been modified to investigate attentional bias towards emotional words (i.e., those carrying stronger arousal and valence ratings). First, in samples of populations with no diagnosed conditions, emotional words generally produce greater interference, and therefore, slower reaction times, in naming the ink colour of words (Dresler et al., 2009; Mckenna & Sharma, 1995; Watts, McKenna, Sharrock, & Trezise, 1986).

The emotional Stroop has been further modified by taking individual differences into account and comparing subgroups in attentional processing of stimuli. One of the earliest emotional Stroop studies (Mathews & MacLeod, 1985) was a modified Stroop task that included words with high emotional valence (e.g., money, freedom). Participants consisted of two groups: 24 participants with diagnosed anxiety and a control group of 24 participants reporting no emotional difficulties due to anxiety. In the task, all participants

where anxious participants were slower to identify the ink colour of all the words, irrespective of word type. Secondly, a group by word type interaction was shown, where responses to identify the ink colour of social and physical threat words were slower in participants with a diagnosis of clinical anxiety. Mathews and MacLeod explained these findings in the context of an attentional bias to threat where the current emotional state of the anxious participants resulted in anxiety words being more capable of capturing their attention. Further, Dresler et al. (2009) investigated whether valence (positive or negative) or arousal level was more likely to provoke emotional attentional bias, whilst state

(temporary) and trait (consistent) anxiety were monitored. Negative and positive words similar in arousal level were used. Results indicated that emotional words elicited longer reaction times than neutral words, but that there was no difference for valence (positive and negative emotional words). Regarding anxiety, state anxiety affected emotional interference, but trait anxiety did not. Finally, emotional words were recalled and recognised significantly more than neutral words.

The literature shows that people demonstrate a general bias towards threat when they have no diagnosed conditions (Dresler et al., 2009; Mckenna & Sharma, 1995; Watts, McKenna, Sharrock, & Trezise, 1986) and this bias is even more robust in individuals with anxiety compared to non-anxious individuals (Fox, Russo & Dutton, 2006; Koster,

Crombez, Verschuere, Van Damme, & Wierserna, 2006; Mathews, A. & MacLeod, 1985; Ouimet, Gawronski & Dozois, 2009). As the emotional Stroop literature has expanded to investigate other diagnosed conditions, studies have shown that participants are slowed when presented with a words pertaining to addictions (Cane et al., 2009; Cox et al., 2006; Fadardi & Cox, 2009; Field, Munafo & Franken; 2009; Waters et al., 2003) and depression (Kerr, Scott & Phillips, 2005; Mitterschiffthaler et al., 2008).

Chapter 1 introduced TTM in the context of a behavioural addiction. The addiction related Stroop task has been used to investigate attentional biases in several addictive

behaviours, namely smoking and alcohol. Fadardi and Cox (2009) used a computerised Alcohol-Stroop test to investigate the effects of alcohol on social (N=40), hazardous (N=89), and harmful (N=92) drinkers’ attention. Hazardous and harmful drinkers demonstrated slower reaction times than social drinkers in naming the ink colour of

alcohol-related words indicating that overindulgence in alcohol is related to attentional bias towards alcohol-related words. In a similar study on smoking behaviours, Cane et al. (2009) carried out an addiction-related Stroop task with 3 groups of participants: current smokers (N=21); those who had abstained for 24 hours and were trying to quit (N=21); and non-smokers (N=22). Current smokers and those who were trying to quit demonstrated similar attentional biases demonstrated by slower response times to smoking-related words. A second modified Stoop study was then conducted for marijuana smokers (N=17) compared with non-marijuana smokers (N=15) using marijuana-related words. A similar pattern of results was found as in study 1: marijuana-related words elicited slower response times in marijuana smokers than non-marijuana smokers.

The studies above strongly indicate that current drinking and smoking status can predict attentional biases (as demonstrated by slower response times) towards substance- related stimuli. However, might the relationship between attentional biases and substance use be bidirectional (i.e., could attentional biases also predict subsequent substance-use behaviours)? In a sample of 158 smokers, Waters et al. (2003) investigated whether attentional biases towards smoking-related stimuli might not only be a result of current smoking status, but also predictive of future smoking behaviours. An attentional bias to tobacco cues as demonstrated by slowed reaction times and more errors was found to be a predictor of relapse and subsequent smoking in participants. Field, Munafo and Franken (2009) also explored the potential bi-directional relationship between tobacco cues and attentional biases by carrying out a meta-analysis investigating associations of self-report

cravings in substance abuse with attentional bias indicators. The results showed that although the correlation was weak, attentional biases and cravings were related.