Evidence for an encounter expectancy bias in fear of spiders

Abstract

Whereas research has demonstrated that phobic or fearful individuals overestimate the likelihood of incurring aversive consequences from an encounter with feared stimuli, it has not yet been systematically investigated whether these individuals also overestimate the likelihood (i.e., the frequency) of such encounters. In the current study, spider-fearful and control participants were presented with background information that allowed them to estimate the overall likelihood that different kinds of animals (spiders, snakes, or birds) would be encountered. Spider-fearful participants systematically overestimated the likelihood of encountering a spider with respect to the likelihood of encountering a snake or a bird. No such expectancy bias was observed in control participants. The results thus strengthen our idea that there indeed exist two different types of expectancy bias in high fear and phobia that can be related to different components of the fear response. A conscientious distinction and examination of these two types of expectancy bias are of potential interest for therapeutic applications.

Keywords:

• Fear of spiders
• Expectancy bias
• Risk of encounter
• Ratings

Acknowledgements

This research was supported by grant PZ00P1_121590 of the Swiss National Science Foundation to TA.

Notes

¹Although our participants met the DSM-IV and ICD-10 criteria for spider phobia, most of them were not seeking treatment. Therefore, and because supplementary questions addressing the degree of interference with daily functioning were not asked, we use the term spider fearful instead of spider phobic throughout the manuscript.

²Note, however, that a highly similar effect was also present in the control group. Although an ANOVA performed for the probability range 0–25% in the control group fell just short of demonstrating a significant effect of Animal, F(2, 32) = 2.93, p=.07, η²=.15, these participants displayed a tendency to indicate higher encounter expectancies for both spiders and snakes as compared with birds (cf. Figure 1c). Therefore, this result may also be explained by the concept of biological preparedness, suggesting that we are particularly prone to experience threat in response to animals having played an important role for survival in human evolution.