Thesis (MA) -- University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Judgement of risk for negative events in certain situations was investigated in a group of emergency medical service (EMS) personnel with a diagnosis of posttraumatic stress disorder (PTSD; n = 27) and a group without PTSD (n = 74). Participants completed the PTSD Symptom Scale: Self-Report version (Faa, Riggs, Dancu, & Rothbaum, 1993), an EMS work experiences questionnaire, the Beck Depression Inventory (Beck, Rush, Shaw, & Emery, 1979), and an event probability questionnaire designed to assess judgement of risk. Participants with PTSD overestimated amount of risk involved in comparison to participants without PTSD, thereby demonstrating a judgement bias for risk related events. The present study found that the judgement bias in PTSD participants extended to include not just external harm related events but also general negative events (without potential threatening/harmful consequences), negative social events, and negative workrelated events. Of the posttraumatic symptomatology assessed, avoidance symptomatology was found to be the best predictor of judgement bias. The results of the present study are discussed in terms of the cognitive clinical psychology theories of PTSD, which predict the manifestation of judgement bias in PTSD, and cognitive experimental psychology explanations of the effect of negative emotional states on judgement processes. / AFRIKAANSE OPSOMMING: Oordeeloor risiko vir negatiewe gebeurtenisse in sekere situasies is ondersoek by "n groep mediese nooddienspersoneel met "n diagnose van posttraumatiese stresversteuring (PTSV; n = 27) en "n groep sonder PTSV (n = 74). Deelnemers het die PTSD Symptom Scale: Self-Report version (Foa, Riggs, Dancu, & Rothbaum, 1993), "n mediese nooddiens werkservaringe-vraelys, die Beck Depression Inventory (Beck, Rush, Shaw, & Emery, 1979), en "n gebeurtenis-waarskynlikheidsvraelys wat opgestel is om oordeeloor risiko te meet, voltooi. Deelnemers met PTSV het die mate van risiko betrokke oorskat in vergelyking met deelnemers sonder PTSVen sodoende "n beoordelingsydigheid vir risiko-verbandhoudende situasies gedemonstreer. In die huidige studie is gevind dat beoordelingsydigheid by PTSV deelnemers nie beperk was tot eksterne skade-verbandhoudende gebeurtenisse nie, maar dat dit ook veralgemeen het na algemene negatiewe gebeurtenisse (sonder potensieel skadelike gevolge), negatiewe sosiale gebeurtenisse, en negatiewe werksverwante gebeurtenisse. Daar is gevind dat, wat PTSV-simptomatologie betref, vermyding die beste voorspeller van beoordelingsydigheid was. Die resultate van die huidige studie word bespreek in terme van kognitiewe klinies-sielkundige teorieë van PTSV, wat die aanwesigheid van beoordelingsydigheid voorspel, en kognitiewe eksperimentele-sielkunde verklarings van die effek van negatiewe emosionele toestande op beoordelingsprosesse.