The Schizophrenia Proneness Instruments (for adults, SPI-A; for children and adolescents, SPI-CY) have their origin in the basic symptom concept first described by Gerd Huber. Basic symptoms are subtle, subclinical self-experienced disturbances in drive, stress tolerance, affect, thinking, speech, perception and motor action, which are phenomenologically clearly distinct from (attenuated) psychotic symptoms. They can be present before the first psychotic episode, between and after psychotic episodes, even during psychotic episodes themselves. They are thought to be the most immediate psychological expression of the neurobiological disturbance underlying the development of psychosis – thus the term ‘basic’.

Basic symptoms are phenomenologically different from normal, non-pathological fluctuations in mental state known to the child/adolescent/adult from what s/he considers his/her normal self, and thus are clearly distinguishable from subtle disturbances described as traits in genetic high-risk persons.
The SPI-CY can be assessed from the age of 8 onwards, yet some basic symptoms require a higher cognitive-developmental state and thus should rather not be assessed before the age of 13. Although their subjective perception is generally a main characteristic of basic symptoms, particularly for their assessment in children and younger adolescents, the SPI-CY offers the possibility to integrate information of parents or carers. Such third-party information, however, should only support the exploration of the child/adolescent and is not meant to replace it.

Link to various language versions of the Schizophrenia Proneness Instruments