فراتر از ترس و تنفر: نقش (اتوماتیک) ارتباط مربوط به آلودگی در عنکبوت هراسی

This study explored the role of threat and contamination-related associations in spider phobia. Treatment-seeking (n=60) and non-phobic (n=30) individuals completed threat and disgust-related Implicit Association Tests (IATs). Phobic individuals were assessed before and after one session of 2.5 h in vivo exposure. To differentiate actual treatment effects from test–retest effects on the IAT, half of the phobic individuals completed the IAT twice before treatment. Results showed that: (1) threat and contamination associations similarly distinguished between phobic and non-phobic participants on self-reports and IATs; (2) only self-reported threat associations incrementally predicted participants’ overt avoidance behavior next to self-reported global affective associations; (3) self-reported associations were significantly reduced following treatment; (4) IAT-effects showed no significant reduction following treatment, and no evidence was found for an additional treatment-induced change over and above test–retest effects.

Traditionally small animal fears, like fear of spiders, have been conceptualized in terms of a predator-defense mechanism, functioning to avoid being attacked or physically harmed (Öhman, Dimberg, & Öst, 1985). More recently fear of spiders has also been linked with disease-avoidance (e.g., de Jong, Peters, & Vanderhallen, 2002; Matchett & Davey, 1991). Meanwhile, fear rather than disgust seems to be the prevalent emotion in spider distress (e.g., Sawchuk, Lohr, Westendorf, Meunier, & Tolin, 2002; Thorpe & Salkovskis, 1998) leading some researchers to conclude that a disease-avoidance conceptualization of spider distress is inappropriate (Edwards & Salkovskis, 2006). However, the disease-avoidance conceptualization of spider distress does not dispute that fear is the dominant response, but implies that the focus of the fear is related to unwanted contact with a disgusting object rather than to physical harm (e.g., van Overveld, de Jong, & Peters, 2006). Fear may result from the expectation of a disgust-related as well as from a harm-related catastrophe. In line with this, de Jong et al. (2002) found that sensitivity to contagion was the single best predictor of elicited fear during spider imagery. Because the emotions of fear and disgust thus seem to be partly confounded (see also Woody & Teachman, 2002), research into the (unique) contribution of these emotions to spider distress cannot reveal why spider phobic individuals are actually distressed by spiders. To answer that question we should step beyond the emotional expressions of fear and disgust and explore how spiders are mentally represented. That is, what kind of catastrophe or negative attributes do spider phobic individuals associate with spiders? Traditionally such associations and beliefs are addressed using self-report measures (e.g., Arntz, Lavy, van den Berg, & van Rijsoort, 1993). Recently however, researchers have started complementing self-report measures with indirect measures of automatic associations. Indirect measures use task performance rather than verbal reports to infer the associations of interest and may therefore capture associations that are difficult to verbalize while at the same being less susceptible to self-presentational concerns and experimental demand. Teachman, Gregg, and Woody (2001) were the first to apply indirect measures to explore automatic spider-related associations. They used the Implicit Association Test (IAT: Greenwald, McGhee, & Schwartz, 1998) to assess multiple evaluative associations with spiders and snakes in spider and snake phobic individuals. Their results suggest that automatic disgust and danger associations differentiate between both phobic groups. In a subsequent study, Teachman and Woody (2003) also found that spider disgust-related IAT-effects were significantly reduced following exposure treatment. These findings suggest that automatic spider-disgust associations are involved in spider distress. However, there are two reasons why it would be important to further examine this issue. Firstly, IAT-effects partly reflect associations toward the contrast that is used. Teachman et al. (2001) and Teachman and Woody (2003) used snakes as the contrast category because snakes and spiders share a comparably negative societal connotation. Yet, to interpret what it means if you find that, for instance, spiders are more strongly associated with disgust than are snakes, you will need to know how disgusting snakes are. If snakes are not or hardly associated with disgust, then the spider-disgust association does not need to be strong at all to obtain this effect. As there may be strong individual differences in the extent to which snakes are associated with disgust, this category provides no unequivocal anchor against which to interpret the IAT-effects. The second issue concerns the absence of a (phobic) no-treatment control group (TCG). Even though Teachman and Woody (2003) used a control task that remained stable over the course of treatment, it cannot be ruled out that the changes on the spider-related IAT are due to test–retest (e.g., learning) effects rather than to treatment specific effects (cf. Thorpe & Salkovskis, 1997). This study aimed to more comprehensively assess the role of (automatic) threat and contamination-related associations in spider phobia. These associations were assessed in phobic and non-phobic individuals using self-report measures and IATs. To provide more unequivocal anchors against which to interpret the IAT-effects we employed contrast categories that are prototypical of the attribute dimension we aimed to assess. We used ‘maggots’ and ‘weapons’ as the contrast categories to assess disgust/contamination-related and threat/harm-related associations, respectively. The idea was that if spiders are found to be more strongly associated with ‘dirty’ or ‘threatening’ than a prototypically dirty or threatening contrast (i.e., maggots or weapons), then spiders must be quite strongly associated with that attribute. According to this reasoning these prototypical contrasts should allow for a more straightforward interpretation of the effects. The malleability of these associations was explored over the course of a one-session exposure in vivo treatment. If (automatic) threat and contamination-related associations are involved in spider phobia, a successful treatment is expected to be accompanied by a reduction in the strength of these associations. To control for test–retest effects on the IAT half of the phobic individuals completed the IAT twice before receiving treatment. No self-report measures were included at retest because, due to people's tendency to answer consistently, it seems unlikely that retest effects would emerge even if they exist. In addition, several studies have shown that self-reports of spider fear and the BAT remain stable over a waiting period (e.g., Dewis et al., 2001; Thorpe & Salkovskis, 1997). Therefore, together with pragmatic considerations concerning time and participant burden, only the IAT was included at retest.

All analyses are based on IAT-effects calculated with the now widely used algorithm proposed by Greenwald, Nosek, and Banaji (2003). Note in passing that for all analyses below the pattern of results was similar when using the traditional algorithm (Greenwald et al., 1998). We report the recommended D3-measure (for details see Greenwald et al., 2003). IAT-scores were calculated so that positive effects indicate relatively fast responses when spiders shared the response key with either dirty or threatening. The IAT-effects are reported in Table 1. The IAT-effects are similar to Cohen's d effect size and can be interpreted as the strength of the difference between both critical IAT phases. The split-half reliability of the presently used IAT's was good with Spearman–Brown corrected correlations between test-halves ranging from 0.68 to 0.92 (M=0.82).