There is now considerable evidence that phobic responding is associated with a bias towards expecting aversive or traumatic outcomes following encounters with the phobic stimulus (e.g. Davey, 1995). In terms of conditioning contingencies, this can be described as a bias towards expecting an aversive or traumatic outcome (the unconditioned stimulus - UCS) following a phobic stimulus (the conditioned stimulus - CS). Research into the role of UCS expectancy biases in the development and maintenance of specific phobias has three basic requirements. First, it is not clear whether the ues expectancy biases evidenced in specific phobias represent a stimulus specific response or a more generalised associative phenomenon. Second, it is not clear what dispositional or state factors might contribute to the development and maintenance of such ues expectancy biases. Third, it is not clear what type of cognitive mechanisms might underlie UCS expectancy biases. This thesis uses a thought experiment version of a threat conditioning procedure to explore these requirements. The key findings indicate that spider phobics tend to overestimate the likelihood of aversive outcomes following phobic, but not other fear relevant stimuli, and tend to underestimate the likelihood of aversive outcomes following fear irrelevant stimuli in comparison to non-phobic controls. This dichotomous ues expectancy bias is mirrored both in the evaluation of stimuli in terms of dangerousness and valance, and in the generation of harm and safety cues with regards to these stimuli. Both positive and negative mood states, but not arousal states contributed to ues expectancy inflation, and in the case of revulsive animals induced state disgust also increased reported ues expectancies. The thesis concludes with an evaluation of the role of UCS'S expectancies in the development and maintenance of specific phobias, and a discussion of the implications of these findings for our understanding of the information processing mechanisms underlying the specific phobias.

Specifik fobi är en vanlig psykiatrisk åkomma som kan leda till stora individuella begränsningar. Symtomen kan framgångsrikt behandlas med kognitiv beteendeterapi där 85–90 % blir kliniskt signifikant förbättrade. Forskning påvisar lovande behandlingsutfall för virtuell exponeringsbehandling (VRET) mot spindelfobi. Tekniken är intressant då den kringgår de problem med anskaffning och förvaring av fobiska stimuli som sedvanlig behandling medför och dessutom kan innebära ökad tillgänglighet och flexibilitet vid behandling. Syftet med föreliggande studie är att jämföra behandlingseffekten av ensessionsbehandling (OST) med en nyutvecklad spelifierad virtuell exponeringsbehandling (VIMSE), som sker under en fristående behandlingssession. Totalt randomiserades 73 deltagare mellan de två behandlingsmetoderna. Båda behandlingarna medförde statistiskt signifikanta förbättringar med stora effektstorlekar för såväl det beteendetest (BAT), som utgjorde det primära utfallsmåttet (OST d = 1,94; VIMSE d = 1,41), som för de sekundära utfallsmåtten Spider Phobia Questionnaire och Fear of Spiders Questionnaire. OST resulterade i signifikant fler kliniskt signifikant förbättrade än VIMSE. / VIMSE (VIrtual reality Method for Spider phobia Exposure therapy)

To study of cognitive fear networks and associations, indirect experimental paradigms like the Implicit Association Test (IAT, Greenwald et al., 1998) or the Extrinsic Affective Simon Task (EAST, De Houwer, 2003) may be helpful, as they promise to assess the structure of specific associations using a performance based approach without having to ask the participant for a verbal report. Three studies investigated the usefulness and characteristics of IAT and EAST. The aim of the first study was to measure fear associations towards spiders among spider phobic and non-phobic participants as well as in a group of spider enthusiasts. Results indicate that the IAT paradigm is sensitive to the strength of fear relevant associations and able to predict anxious behavior beyond the predictions of direct measures such as questionnaires. The second study focused on some of the mechanisms that underlie IAT effects. With a newly developed masked IAT, these experiments investigated the influences of individual stimuli and superordinate categories on IAT performance. Besides theoretical implications, the results also provide practical, relevant applications for the use of IAT experiments. A third study applied the EAST to investigate how different context conditions lead to differential activation of cognitive schemata in fear of spiders. One can conclude that the impact of automatic threat associations depends on the activated context, and that the EAST is suitable for the assessment of fear associations and their current activation level. This dissertation leads to the conclusion that the performance based methodology of the IAT and EAST is a useful and practical approach to reflect fear associations in phobia indirectly. At this point, the use of indirect measures is still at its beginning, and requires intensive methodological and theoretical efforts. These paradigms, however, may become useful for possible implications in psychopathology and other fields of psychology.

To study of cognitive fear networks and associations, indirect experimental paradigms like the Implicit Association Test (IAT, Greenwald et al., 1998) or the Extrinsic Affective Simon Task (EAST, De Houwer, 2003) may be helpful, as they promise to assess the structure of specific associations using a performance based approach without having to ask the participant for a verbal report. Three studies investigated the usefulness and characteristics of IAT and EAST. The aim of the first study was to measure fear associations towards spiders among spider phobic and non-phobic participants as well as in a group of spider enthusiasts. Results indicate that the IAT paradigm is sensitive to the strength of fear relevant associations and able to predict anxious behavior beyond the predictions of direct measures such as questionnaires. The second study focused on some of the mechanisms that underlie IAT effects. With a newly developed masked IAT, these experiments investigated the influences of individual stimuli and superordinate categories on IAT performance. Besides theoretical implications, the results also provide practical, relevant applications for the use of IAT experiments. A third study applied the EAST to investigate how different context conditions lead to differential activation of cognitive schemata in fear of spiders. One can conclude that the impact of automatic threat associations depends on the activated context, and that the EAST is suitable for the assessment of fear associations and their current activation level. This dissertation leads to the conclusion that the performance based methodology of the IAT and EAST is a useful and practical approach to reflect fear associations in phobia indirectly. At this point, the use of indirect measures is still at its beginning, and requires intensive methodological and theoretical efforts. These paradigms, however, may become useful for possible implications in psychopathology and other fields of psychology.