Spider phobics more easily see a spider in morphed schematic pictures

Behavioral and Brain Functions Spider phobics more easily see a spider in morphed schematic pictures Iris-Tatjana Kolassa 1 2 Arlette Buchmann 2 Romy Lauche 2 Stephan Kolassa 0 Ivailo Partchev 3 Wolfgang HR Miltner 2 Frauke Musial 2 0 Operations Research, Institute of Applied Mathematics, Friedrich Schiller University Jena , Ernst-Abbe-Platz 2, 07743 Jena , Germany 1 Clinical & Neuropsychology, University of Konstanz , P.O. Box 5560, 78457 Konstanz , Germany. 2 Institute of Psychology, Biological & Clinical Psychology, Friedrich Schiller University Jena , Am Steiger 3, 07743 Jena , Germany. 3 Institute of Psychology, Methodology & Evaluation Research, Friedrich Schiller University Jena , Am Steiger 3, 07743 Jena , Germany Background: Individuals with social phobia are more likely to misinterpret ambiguous social situations as more threatening, i.e. they show an interpretive bias. This study investigated whether such a bias also exists in specific phobia. Methods: Individuals with spider phobia or social phobia, spider aficionados and non-phobic controls saw morphed stimuli that gradually transformed from a schematic picture of a flower into a schematic picture of a spider by shifting the outlines of the petals until they turned into spider legs. Participants' task was to decide whether each stimulus was more similar to a spider, a flower or to neither object while EEG was recorded. Results: An interpretive bias was found in spider phobia on a behavioral level: with the first opening of the petals of the flower anchor, spider phobics rated the stimuli as more unpleasant and arousing than the control groups and showed an elevated latent trait to classify a stimulus as a spider and a response-time advantage for spider-like stimuli. No cortical correlates on the level of ERPs of this interpretive bias could be identified. However, consistent with previous studies, social and spider phobic persons exhibited generally enhanced visual P1 amplitudes indicative of hypervigilance in phobia. Conclusion: Results suggest an interpretive bias and generalization of phobia-specific responses in specific phobia. Similar effects have been observed in other anxiety disorders, such as social phobia and posttraumatic stress disorder. - Background Cognitive biases have been assumed to play an important role in the development and maintenance of anxiety disorders. Biases in anxiety disorders have been broadly categorized in empirical research as biases affecting the three general stages of information processing (1) attention and the encoding of information; (2) elaboration and interpretation; and (3) storage and retrieval from memory [1,2]. An example for an interpretive/judgmental bias is the negative interpretation bias found in particular in social phobics. Several studies showed that individuals with social phobia are more likely to misinterpret (ambiguous) social situations as more threatening and to draw more negative inferences from social stimuli than controls [3-5]. In spider phobia, Becker & Rinck [6] found a generalized interpretive bias by presenting pictures of spiders, beetles or butterflies interspersed with neutral pictures for 14 ms each. Spider phobic participants were more likely to report having seen a spider or a beetle, which was interpreted as applying a more liberal criterion both to highly negative spiders and to slightly negative beetles. The concept of stimulus generalization, first introduced by Pavlov [7], is closely related to interpretive biases. Stimulus generalization refers to the fact that conditioning of a particular stimulus will result in generalization of this conditioning to other, similar stimuli. This generalization leads to similar yet weaker responses to new stimuli compared to the originally conditioned stimulus [e.g., [8]]. Processing of fear-relevant stimuli in specific phobia Several PET, functional MRI and ERP studies have investigated the processing of fear-relevant stimuli in phobic patients (e.g. [9-15]). Fredrikson et al. [9] were among the first to report elevated regional cerebral blood flow (rCBF) in the visual associative cortex of snake phobics who viewed phobic, as compared to neutral and aversive stimuli. The elevated rCBF in the visual cortex of phobics in response to their feared object [9,10] is in line with studies reporting more extensive activation of the visual cortex when viewing highly emotional (arousing) stimuli [e.g., [16,17]]. Similarly, ERP studies revealed enlarged late positive potentials in spider phobic individuals in response to feared objects [13-15]. These results are in accordance with the larger parietal cortical positivities observed in response to highly emotional (arousing) stimuli in nonphobic individuals (e.g., [18,19]). Whereas the influence of emotional valence/arousal on late ERP components is well-documented, early ERP components have not been fully investigated. Miltner et al. [15] observed no phobiaspecific effect on early ERP components (N1, P2, N2) when spider or snake phobic individuals were processing pictures of feared objects. However, in a study investigating the processing of schematic spider and flower stimuli consisting of the same visual elements, Kolassa et al. [14] found generally enhanced P100 amplitudes in individuals with spider phobia and individuals with social phobia, as compared to non-phobic controls. These observations were interpreted as evidence for an increased (cortical) hypervigilance for incoming stimuli in phobic patients in general. Furthermore, all groups, whether spider phobic or not, showed faster identification of and larger N170 amplitudes in response to schematic spider versus flower pictures, which may reflect a general advantage in the processing of fear-relevant features. Fear-relevant features and Gestalt properties hman [20] postulated the existence of specific feature detectors that are preferentially sensitive to elementary threat features which were significant for survival during evolution. If such a threat feature is detected, the stimulus automatically and preattentively activates the arousal system and becomes tagged for preferential evaluation by a succeeding significance evaluation system [20]. However, as hman et al. [[21], p. 475] admit, "such elementary threat features [...] still remain to be specified." As facial expressions signaling social threat should presumably have been of evolutionary significance, in recent years facial features that convey threat have been extensively investigated [22-25]. However, which properties make a spider fear-relevant is still unknown. Is it the shape of the body of a spider, its protruding legs, the angle in which the legs are positioned in relation to each other and to the body? Or is it the movement of a spider or a snake that is detected by these feature detectors? Or do the feature detectors respond to still other details of the feared stimulus? The present study attempts to partly fill this (...truncated)