The results of the teacher survey showed that teachers considered the training valuable for their daily teaching practice. The laboratory course was regarded to be most valuable. The course dealing with theoretical principles of the perceptional approach was less advantageous. Approximately 20% of the teachers had changed their beliefs in the use of experiments after the ideas represented in the training program. There were no significant differences between the experimental and control groups in the views regarding the reasons for using experiments in teaching physics. The most important objective for practical work was to enhance students’ learning of concepts. According to teacher interviews, some teachers were influenced by the program and the way experiments could be used in supporting the creation of meanings for concepts. However, some teachers strongly held to their previous beliefs.

The effect of the training program on teachers’ beliefs about the concept of interaction as an organizing principle in teaching mechanics was examined using teacher interviews. The results showed no remarkable effects. However, the explicit use of interaction as a guiding principle in teaching Newtonian mechanics enhanced students’ conceptual understanding of force as measured with the Force Concept Inventory, which was translated into Finnish.

The aims of the thesis were to characterize cognitive functioning in schizophrenia and schizoaffective disorder and to examine whether clinical characteristics are related to cognitive impairment in these disorders. An additional aim was to investigate whether previously identified risk factors for schizophrenia (low and high birth weight, male sex, originating from an internal isolate) are associated with cognitive impairment in families with schizophrenia, and whether the illness or the degree of genetic loading for the illness modifies this relationship.

The present thesis is a part of the Genetic Epidemiology and Molecular Genetics of Schizophrenia in Finland project. Previously the project has focused on the genetic epidemiology of schizophrenia in Finland as a whole and within the genetic isolate, as well as on neuropsychological deficits in schizophrenia patients and their family members, and on the use of neuropsychological variables as endophenotypes in genetic analyses. Schizophrenia patients with a high genetic loading for schizophrenia were identified from nationwide health care registers. In the present thesis, groups of persons with schizophrenia (n = 218), persons with schizoaffective disorder (n = 62) and their unaffected first-degree relatives (n = 438) were investigated. The control group comprised 123 persons and, in the study focusing on the isolate, 112 persons. The participants were diagnosed on the basis of a diagnostic interview and case records from mental health care contacts. The participants underwent a battery of neuropsychological tests, assessing processing speed, executive functions, attention, working memory, verbal learning and memory and verbal ability.

The schizophrenia group demonstrated broad cognitive impairment compared to the control group with large effect sizes. In schizoaffective disorder, broad cognitive impairment with effect sizes ranging from medium to large were detected. Differences in clinical characteristics accounted for the differences in cognitive functioning between the diagnostic groups. Irrespective of diagnosis, patients with severe negative symptoms and a high dose of antipsychotic medication had the most severe cognitive impairment. Both low and high birth weight were associated with more severe cognitive impairment than intermediate birth weight in persons with schizophrenia and their first-degree relatives. Sex differences in cognitive functions were mostly preserved in schizophrenia families when compared to controls despite large cognitive impairment in schizophrenia, and mild cognitive impairment in first-degree relatives. In persons with schizophrenia and their first-degree relatives, persons from the internal isolate had slightly better performance in some of the cognitive measures than persons from the rest of the country. However, no such differences were noticed in the controls.

In conclusion, persons with schizoaffective disorder demonstrated broad cognitive impairment, which was milder than in schizophrenia. The results suggest that symptom severity predicts the level of cognitive impairment in these disorders more accurately than categorical diagnosis does. The results also showed that the assessed schizophrenia risk factors may have distinct associations with cognitive functioning. Low and high birth weight were associated with slightly lower cognitive performance than intermediate birth weight in persons with schizophrenia and in their first-degree relatives. Despite sex differences in illness characteristics, sex did not affect the level of cognitive impairment in persons with schizophrenia or in their first-degree relatives. Originating from an internal isolate was associated with slightly higher cognitive performance than originating from the rest of Finland both in persons with schizophrenia and in their first-degree relatives, but not in the control group. This difference may reflect differences in the genetic aetiology of schizophrenia between the isolate and the rest of Finland.