Code for: Expanding the positivity offset theory of anhedonia to the psychosis spectrum. In: Schizophrenia

Code for: Riehle, M., Pillny, M., & Lincoln, T. M. (2022). Expanding the positivity offset theory of anhedonia to the psychosis continuum. Schizophrenia, 8(1). https://doi.org/10.1038/s41537-022-00251-x Specifically, this is the code for the multilevel linear models used to assess differences between stimulus categories and for estimating Positivity Offset and Negativity Bias.

People with schizophrenia and negative symptoms show diminished net positive emotion in low-arousing contexts (diminished positivity offset) and co-activate positive and negative emotion more frequently (increased ambivalence). Here, we investigated whether diminished positivity offset and increased ambivalence covary with negative symptoms along the continuum of psychotic symptoms. We conducted an online-study in an ad-hoc community sample (N = 261). Participants self-reported on psychotic symptoms (negative symptoms, depression, positive symptoms, anhedonia) and rated positivity, negativity, and arousal elicited by pleasant, unpleasant, and neutral stimuli. The data were analyzed with multilevel linear models. Increasing levels of all assessed symptom areas showed significant associations with diminished positivity offset. Increased ambivalence was related only to positive symptoms. Our results show that the diminished positivity offset is associated with psychotic symptoms in a community sample, including, but not limited to, negative symptoms. Ecological validity and symptom specificity require further investigation.