The thesis addresses Semantic Verbal Fluency test and its potential as a diagnostics of cognitive deficit at schizophrenic population. Deficit of cognitive functions, presently considered as a core symptom of this disorder, substantially impacts daily life functioning. In particular, discriminant validity of Semantic Verbal Fluency test is examined in a mentally and neurologically healthy population as well as patients diagnosed with schizophrenia aged 18 to 40 years (N=339). Furthermore, results of profound analysis using a qualitative scoring system in a selected sample group (N=47) are presented. Moreover, the study investigates the association of selected demographic variables (gender, age, years of education) with results of Semantic Verbal Fluency test. Results of our statistical analysis reveal that patients diagnosed with schizophrenia performed significantly worse than healthy controls in all examined variables (total word count, total number of semantic clusters, total number of switches, mean cluster size, percent words in clusters, ratio of cluster switches) as compared with mentally and neurologically healthy subjects. Comparable results of the two research groups were attained solely in "number of hard switches" variable. Our results further indicate a significant association between...