The role of non-semantic factors in semantic satiation effect in schizophrenia

Background and Objectives: Semantic satiation is defined as the subjective experience of the loss of access to the meanings of words or images caused by prolonged and quick repetitions of the material. Previous researches indicated that the semantic satiation of words and images occurs faster in schizophrenics than in healthy subjects. Individuals suffering from schizophrenia reveal the tendency to lose of access to the meaning of words after fewer words repetition than healthy controls. The aim of the research was to establish whether the semantic satiation of images in schizophrenia is the effect of the loss of meanings of images or is caused by non - semantic factors i.e. fatiguing experimental procedure. Methods: It was assumed that in conditions where the participant’s level of fatigue was parallel to the fatigue observed in the research on semantic satiation and the meaning of satiated images was not required for semantic decisions, schizophrenic patients and healthy controls would not reveal the semantic satiation effect defined as an increase in reaction time. Two groups of participants: patients suffering from schizophrenia (10 women and 10 men, average age 30) and healthy controls (9 female and 9 male, average age 30.7) were shown 80 trails. Each one of them consisted of a satiated image which appeared repeatedly on the computer screen, and a non – satiated image accompanied by a written word, which were shown simultaneously after the final presentation of the satiated image. The participants’ task was to decide whether the written word named the object presented on the non – satiated picture correctly. The participants did not make any decisions on the basis of satiated images. Results: The results obtained confirmed the hypothesis. In conditions where participants were shown the images flashing on the computer screen but were not required to make a semantic decision related to those images, their reaction time to subsequently presented stimuli did not lengthen. Conclusions: The results confirmed the hypothesis that the semantic satiation effect in schizophrenia is a semantic phenomenon and is not related to non – semantic factors such as the subjects’ fatigu