The Role of Top-Down and Bottom-Up Processing in Auditory False Perceptions: A Signal Detection Analysis

There is a tendency in the literature to find people with a high hallucination proneness to have significantly lower response bias but no significant difference for sensitivity compared to people with low hallucination proneness, when performing a signal detection theory (SDT) task. However, results have varied across studies, and the relation is poorly understood. We wanted to increase our understanding by investigating the effect of different levels of semantic expectation and different types of noise on hallucinatory reports among those with high and low hallucination proneness. A large student sample was screened using a revised version of the Launay-Slade Hallucination Scale (LSHS). Students with high and low hallucination proneness were asked to take part in the second phase of the study. In this phase they performed an auditory SDT task where both the semantic expectation of sentences and the noise were manipulated. Participants also completed measures of perception anomalies (Cardiff Anomalous Perceptions Scale), fantasy proneness (Creative Experiences Questionnaire), suggestibility (Multidimensional Iowa Suggestibility Scale), aberrant salience (Aberrant Salience Inventory), and encoding style (Encoding Style Questionnaire). Results showed that participants in the high hallucination proneness group had a lower response bias compared to participants in the low hallucination proneness group when there was a combination of a high level of semantic expectation and Bergen noise. This suggests that both bottom-up and topdown factors are needed to elicit auditory hallucinatory experiences. Furthermore, hallucination proneness, aberrant salience and encoding style all had significant, negative correlations with response bias, indicating that they could all be implicated in the occurrence of auditory hallucinatory experiences.Det er en tendens i litteraturen til å finne at folk med høy hallusinasjonstendens har signifikant lavere respons bias, men ingen signifikant forskjell for sensitivitet sammenlignet med folk med lav hallusinasjonstendens, når de utfører en signaldeteksjonsoppgave. Til tross for den generelle tendensen har resultatene variert på tvers av studier, og forholdet er lite forstått. Vi ønsker å øke vår forståelse ved å undersøke effekten av ulike nivåer av semantisk forventning og ulike typer støy, på hallusinasjonsrapporter blant personer med høy og lav hallusinasjonstendens. Et stort utvalg studenter ble forhåndstestet ved å bruke en revidert versjon av Launay-Slade Hallucination Scale (LSHS). Studentene med høy og lav hallusinasjonstendens ble spurt om å ta del i den andre fasen av studien. I denne fasen utførte de en auditiv signaldeteksjonsoppgave hvor både den semantiske forventningen til setningene og støyen var manipulert. Deltakerne utførte også målinger av persepsjonsavvik (Cardiff Anomalous Perceptions Scale), fantasitendens (Creative Experiences Questionnaire), suggestibilitet (Multidimensional Iowa Suggestibility Scale), avvikende betydning (Aberrant Salience Inventory), og innkodingsstil (Encoding Style Questionnaire). Resultatene viste at deltakere i høy hallusinasjonstendensgruppen hadde en lavere respons bias sammenlignet med lav hallusinasjonstendensgruppen når det var en kombinasjon av høyt nivå av semantisk forventning og Bergenstøy. Dette peker på at både bottom-up og top-down faktorer er nødvendige for å fremkalle auditive hallusinasjons-opplevelser. Videre hadde hallusinasjonstendens, avvikende betydning og innkodingsstil alle signifikante negative korrelasjoner med respons bias, noe som indikerer at de alle ser ut til å være impliserte i forekomsten av auditive hallusinasjons-opplevelser.Masteroppgave i psykologiMAPSYK36

The Role of Top-Down and Bottom-Up Processing in Auditory False Perceptions: A Signal Detection Analysis

There is a tendency in the literature to find people with a high hallucination proneness to have significantly lower response bias but no significant difference for sensitivity compared to people with low hallucination proneness, when performing a signal detection theory (SDT) task. However, results have varied across studies, and the relation is poorly understood. We wanted to increase our understanding by investigating the effect of different levels of semantic expectation and different types of noise on hallucinatory reports among those with high and low hallucination proneness. A large student sample was screened using a revised version of the Launay-Slade Hallucination Scale (LSHS). Students with high and low hallucination proneness were asked to take part in the second phase of the study. In this phase they performed an auditory SDT task where both the semantic expectation of sentences and the noise were manipulated. Participants also completed measures of perception anomalies (Cardiff Anomalous Perceptions Scale), fantasy proneness (Creative Experiences Questionnaire), suggestibility (Multidimensional Iowa Suggestibility Scale), aberrant salience (Aberrant Salience Inventory), and encoding style (Encoding Style Questionnaire). Results showed that participants in the high hallucination proneness group had a lower response bias compared to participants in the low hallucination proneness group when there was a combination of a high level of semantic expectation and Bergen noise. This suggests that both bottom-up and topdown factors are needed to elicit auditory hallucinatory experiences. Furthermore, hallucination proneness, aberrant salience and encoding style all had significant, negative correlations with response bias, indicating that they could all be implicated in the occurrence of auditory hallucinatory experiences