Symptoms of psychosis have been proposed to form part of a continuous distribution of experiences in the general population rather than being an all-or-nothing phenomenon. Indeed, schizotypal signs have been reported in subjects from non-clinical samples. Emotional processing has been documented to be deficient in schizophrenia. In the present study, we tested the hypothesis whether putatively psychosis-prone subjects would show abnormalities in emotion processing. Based on the extremes of Launay–Slade Hallucination Scale (LSHS) ratings of 200 undergraduate students, two groups of subjects (total N=40) were selected. All 40 participants filled in the Schizotypal Personality Questionnaire (SPQ). We compared both groups on an alexithymia questionnaire and on four behavioral emotional information processing tasks. Hallucination-proneness was associated with an increased subjective emotional arousal and fantasy-proneness. Although no differences between the high and low group were observed on three behavioral emotion processing tasks, on the affective word-priming task presentation of emotional stimuli was associated with longer reactions times to neutral words in high schizotypal subjects. Also, SPQ scores correlated with several emotion processing tasks. We conclude that these findings lend partial support to the hypothesis of continuity between symptoms characteristic of schizophrenia and psychosis-related phenomena in the normal population.
A growing number of studies consider psychosis as a continuum with normal functioning at one end and abnormal functioning (psychosis) at the other end Verdoux and van Os, 2002, Johns and van Os, 2001 and Claridge, 1997. In accordance with this view, Johns and van Os (2001) have reviewed evidence indicating that psychotic signs, often called schizotypal signs or schizotypal traits, are present in healthy people to a certain extent. Schizotypy refers to the personality trait of experiencing ‘psychotic’ symptoms (Claridge, 1997) and schizotypy may be conceptualized as a predisposition to schizophrenia at the level of the organization of the personality Meehl, 1989 and Vollema and van den Bosch, 1995. Such schizotypal traits, e.g., referential thinking and odd or eccentric behavior have been hypothesized to be normally distributed in the non-clinical population (Chapman et al., 1976).
One of the cardinal dysfunctions associated with schizophrenia concerns processing of emotional information (McKenna, 1994), including disturbances in the expression, experience and perception of emotions. Indeed, Kreapelin (1907) regarded emotional disturbances, such as flattened and inappropriate affect, to be characteristic of schizophrenia. Although schizophrenic patients inadequately express emotions Berenbaum and Oltmanns, 1992, Knight and Valner, 1993, Kring et al., 1994 and Kring and Neale, 1996, Kohler et al. (2000) and Myin-Germeys et al. (2000) suggested that the subjective experience of emotion is much less disturbed in schizophrenia.
Sifneos (1973) introduced the term ‘alexithymia’ to describe abnormalities in affect regulation. More specifically, alexithymia refers to difficulties in recognizing, identifying and describing one's own emotions. Thus, alexithymic individuals have impaired affect regulation (Bagby and Taylor, 1997) and may also show specific inabilities to communicate emotions while the experience of emotion might be intact (Kihlstrom et al., 2000). Cedro et al. (2001) demonstrated that schizophrenic patients have higher scores on an alexithymia questionnaire than healthy controls, i.e., they have more problems in identifying and verbalizing their emotions.
With regard to behavioral measures of emotional processing in schizophrenia, deficits in emotion recognition have been found (Edwards et al., 2002). In addition, schizophrenic patients appear to inadequately process facial affect Addington and Addington, 1998 and Streit et al., 2001 and demonstrate a reduced left-perceptual bias in the processing of emotional chimeric faces (Gooding et al., 2001). There might also be a bias towards material with a negative emotional valence, as observed in a study in which hallucinating patients were more sensitive to negative words compared to controls (Johns et al., 2002). Moreover, a recent study (Hoschel and Irle, 2001) reported that negative emotional expressions yield stronger priming effects in schizophrenia patients compared to control subjects (hyperpriming).
