In the wake of limited knowledge on clustering and switching during semantic fluency (SF) in patients with first-episode psychosis (PwFEP), the present study aimed (1) to investigate clustering and switching on SF in PwFEP using more precise statistical procedures and (2) to investigate the possibility of disproportionate clustering patterns across different SF tasks in PwFEP and healthy subjects (HS), as this has been indicated by the current literature on patients with schizophrenia. We recruited 22 PwFEP and 22 HS matched in age, sex distribution, and handedness. All patients were medicated and had a mean illness duration of 1 month (median: 0). Five categories were administered for SF: animals, trees, vegetables, fruits, and musical instruments (60 seconds each). PwFEP produced significantly fewer correct words in the aggregate score, as well as across all categories. The switching rate was significantly higher in PwFEP, but no post hoc comparisons were significant. PwFEP also produced significantly smaller clusters, yet the post hoc comparisons for the tree and fruit task were not significant. A higher switching rate and smaller clusters indicate less efficient functional connectivity within subcategories of the given categories, but not necessarily between the subcategories. Although both less likely to produce a cluster once a switch has been uttered and less likely to produce clusters larger than two words compared to HS, the latter deficit was more pronounced. Possibly, PwFEP might have greater difficulty in processing more concrete compared to more abstract concepts. Finally, our results also indicate that there are category-specific effects on the clustering deficit in PwFEP, possibly demonstrating that PwFEP might show normal performance on executively more demanding SF subtasks. We discuss the results in the context of the hypothesis of semantic hyperactivation in schizophrenia.

Despite both theoretical and empirical linguistics suggesting otherwise, researchers using semantic and phonemic fluency tasks have uncritically assumed that there are no category- or phoneme/letter-specific effects on verbal fluency performance. We recruited 16 young adult subjects and administered two semantic (animals, trees) and two phonemic (K, M) fluency tasks. Executive functions were assessed using the Wisconsin Card Sorting Test (WCST). On the animal compared to the tree task, subjects produced significantly more legal words, had a significantly lower intrusion rate, significantly shorter first-response latencies and final silence periods, as well as significantly shorter between-cluster response latencies. These differences can at least partly be explained by differences in the category sizes, integrity of the categories’ borders, and efficiency of the functional connectivity between subcategories. Switching on the animal but clustering on the tree task were moderately and strongly, respectively, correlated with the WCST. On the K compared to the M task, subjects produced significantly more legal words and had significantly shorter between-cluster response times. Counterintuitively, a corpus analysis revealed there are more words starting with the ⟨m⟩ compared to ⟨k⟩ in the experimental language. Performances on the K and M tasks were very limitedly associated with the WCST. Our results have important implications for research utilizing verbal fluency, indicating that researchers should pay close attention to the types of semantic categories and phonemes/letters within neuropsychological assessments, as well as in the context of reviews and meta-analyses. In order to accomplish this adequately, further research on the specificities of different verbal fluency tasks is direly needed.

In schizophrenia, language processing indicates an over-inclusiveness (Chen, 1994; Brebion, 2010) in category (hypernymy and hyponymy) relations. The aim of this study was to examine the preservation of category relations of semantic memory in first-episode and early-course schizophrenia-spectrum psychosis as it offers an insight to foundations of schizophrenia language deficits. The study was conducted in cooperation with the University Psychiatric Hospital Vrapče on 17 patients. The patients' results were correlated with those of a matched control group. The test that was used to conduct the experiment was constructed for the intent of this study, and it consisted of 10 categories, each of which was tested over 5 trials. For each trial, participants had to choose a member of a presented category. Possible answers included the target word (a category member such as hobotnica 'octopus'), a pragmatic-semantically related distractor (e.g. more 'sea'), a lexical-semantically related distractor (e.g. krak 'tentacle'), and an unrelated distractor (e.g. truba 'trumpet'). None of the unrelated distractors in either group were selected as category members. Although both pragmatic-semantically related and lexical-semantically related distractors were classified as category members more often in the patient group, pragmatic-semantically related distractors were chosen more often than lexical-semantically related distractors. While the results support the theory that concept representations in the semantic memory are not completely lost, the question remains whether the representations are degraded or whether there is a difference in search and retrieval processes in patients with first episode psychosis (FEP) when compared to a healthy control group.

Language deficits in psychosis, and in schizophrenia, are presumed to be due to increased activation and connectivity of the semantic memory, which is determined by lexical-semantic features of concepts. The aim of this study was to analyse the influence of shared lexical-semantic features on language processing in patients with first-episode and early-course psychosis. The study included 15 Croatian-speaking patients from the University Psychiatric Hospital Vrapče, Zagreb, diagnosed with first-episode and early-course psychosis and a healthy control group. The subjects performed a lexical-semantic decision task in which the primes and the target words were either related as hypernym and hyponym or were unrelated, and in which the target words represented either animate or inanimate concepts. Two results analyses were conducted: one on the taxonomic (hyponym-hypernym) condition and one on the animacy (living/non-living stimulus) condition. The patient group was less accurate on the taxonomy condition because the taxonomy relations were dependent on their shared features. The patients' activation of shared features was higher, and their inhibition was reduced. Consequently, the patients will have a greater number of concepts activated and not inhibited. For the inanimate concepts, a high correlation of distinctive features is characteristic, while the animate concepts have a high correlation of shared features. The presupposition is that the greater activation of shared features influenced the patients' answers, so the distinctive features had no influence. Thus, the control group had higher accuracy for inanimate concepts.

Data on clustering and switching during semantic fluency (SF) in patients with first-episode psychosis (PwFEP) are scant. We aimed to investigate (1) clustering and switching on SF in PwFEP using more detailed clustering analyses and (2) the possibility of disproportionate clustering deficits across different SF tasks in PwFEP and healthy subjects (HS), with the latter being suggested by the current literature on patients with schizophrenia. We recruited 22Croatian-speaking PwFEP with schizophrenia features or symptoms and 22 HS matched in age, sex distribution, and handedness. All patients were medicated and had a mean illness duration of 1 month. The categories animals, trees, vegetables, fruits, and musical instruments were administered for SF. PwFEP produced significantly fewer correct words in the aggregate score, as well as across all categories. The switching rate was significantly higher in PwFEP, but no post hoc comparisons were significant. PwFEP also produced significantly smaller clusters, yet the post hoc comparisons for the tree and fruit task were not significant. A higher switching rate and smaller clusters indicate less efficient functional connectivity within subcategories of the given categories, but not necessarily between the subcategories. Although both less likely to produce a cluster once a switch has been uttered and less likely to produce clusters larger than two words compared to HS, the latter deficit was more pronounced. Our results further suggest that PwFEP might show normal clustering performance on some SF tasks. We discuss the results in the context of the hypothesis of semantic hyperactivation in psychoses.