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F Rist

Publications and source records attributed to F Rist.

At least 19 recordsLinked to original sources
PubMed1996

N2, P3 and the lateralized readiness potential in a nogo task involving selective response priming.

Motor inhibition and its correlates in the event-related potential (ERP) are often studied in go/nogo tasks. However, go and nogo trials differ in their motor and their attentional requirements, rendering an interpretation of corresponding changes in ERP components difficult. As an alternative strategy to study motor inhibition, a hybrid choice-reaction go/nogo procedure involving selective response priming was used. Eighteen subjects performed the task. Response time (RT) and error measures as well as the lateralized readiness potential (LRP) indicated that responses were primed by flanker stimuli that were associated with one of the two possible responses. In nogo trials, selective response priming influenced the N2 amplitude whereas the P3 amplitude was unaffected. Because the N2 appeared irrespective of whether an erroneous response was correctable (in go trials) or not (in nogo trials), we conclude that the N2 reflects either the detection or the inhibition of an inappropriate tendency to respond.

Adult↗
PubMed1996

N200 in the flanker task as a neurobehavioral tool for investigating executive control.

Event-related potentials were recorded in a flanker task using arrowheads pointing to the left or to the right as targets and as congruent or incongruent flanker stimuli using squares as neutral flanker stimuli. The onset of the flanker stimuli preceded that of the target stimuli by 100 ms. Lateralized readiness potentials showed response activation below execution threshold in correspondence to the information conveyed by the flanker stimuli. Exclusively, the incongruent flanker condition provoked a N2c, which evolved closely synchronized to the erroneous response. Graded response analyses separating incongruent trials with weak, medium, and strong incorrect response activation revealed that the N2c amplitude covaried with the magnitude of the erroneous response. The N2c in the incongruent compatibility condition of the flanker task thus corresponds to the avoidance of inappropriate responses, possibly reflecting the inhibition of automatically but erroneously primed responses. The results are compatible with studies of error correction, suggesting that efference monitoring is a constituent of executive control.

Adult↗
PubMed1994

Patient Rejection Scale: correlations with symptoms, social disability and number of rehospitalizations.

The Patient Rejection Scale (RPS), which was developed to assess rejecting attitudes and feelings of relatives toward mental patients, was administered to a German sample of 44 family members or significant others living with first-admitted schizophrenics. Both at admission (t0) and 6 months later (t6), the PRS was significantly correlated with the number of rehospitalizations during the first 3 years after admission. In comparison, the association between PRS scores and different measures of psychopathology during the 2-year follow-up period was weak. Thus, rejecting attitudes of patients' relatives seem to imply a higher risk of relapse without substantial medication by symptoms. We suspect that relatives with rejecting attitudes towards a patient might tend to apply for readmission more easily than more accepting relatives.

Adolescent↗
PubMed1994

Selective attention and response competition in schizophrenic patients.

Visual distractibility was studied in schizophrenic patients. Subjects had to respond to target stimuli while they ignored the visual context, which was either congruent, neutral, or incongruent with respect to the target stimulus. Eighteen schizophrenic patients and 18 healthy subjects performed this flanker task. Schizophrenic patients did not show increased distractibility compared with healthy subjects, and both groups showed the same attenuation of visual context effects when the spatial distance between target and flanker stimuli was increased. The two groups showed the same amount of interference by incongruent visual context. Thus, schizophrenic patients did not show enhanced distractibility, spatial extension of attention, or response competition. When flanker and target stimuli were redundant, the responses of schizophrenic patients were less accelerated than those of healthy subjects.

Adult↗
PubMed1994

Error-correcting behavior in schizophrenic patients.

According to Frith (1987) the positive symptoms of schizophrenic patients result from an impaired central monitoring of their own actions. For motor behavior, this impairment implies deficient corrections of erroneous movements. Several studies found that schizophrenic patients did correct erroneous movements less frequently than various control groups. In these studies, movement errors were induced by instructing subjects to alternate between moving a joystick towards a target or away from it. In our study, 27 chronic schizophrenic patients, 27 healthy and 18 alcoholic controls were subjected to a similar task. Spatial and symbolic compatibility between stimuli and responses were varied in order to induce errors. Schizophrenic patients responded more slowly and took more time to reverse wrong movements than both control groups. They did not show fewer error corrections or increased correction latencies. These results did not support the supposed deficit in central monitoring of action. Schizophrenic patients exhibited more short latency movements with multiple changes of movement direction than the control groups. This may indicate a failure to inhibit the initiation of competing responses.

Adult↗
PubMed1994

Reaction time paradigms in subjects at risk for schizophrenia.

Deviant response patterns in experimental reaction time paradigms in schizophrenic probands are well documented. Although simple reaction times are strongly influenced by the current psychopathological status of the proband (e.g. florid psychotic patients versus remitted patients) these influences are less clear for measures obtained from more complex reaction time paradigms. These include the crossover paradigm (reaction time to stimuli presented after constant preparatory intervals in comparison to reaction time to stimuli presented after irregular preparatory intervals) and the modality shift paradigm (reaction time to a stimulus (light or tone) when the modality of the stimulus on the preceding trial was the same compared to when it was different). It is not clear if these peculiarities of response patterns occur as a consequence of the disease or if they represent vulnerability markers for schizophrenia. Both crossover reaction time and modality shift reaction time paradigms were applied to 56 drug free schizophrenics, 45 healthy siblings of these patients and 68 healthy controls. The results indicate that retarded reaction times and the occurrence of the crossover effect as well as of the modality shift effect distinguish schizophrenics and controls. Healthy siblings of schizophrenics differed from healthy controls with regard to the crossover effect but not with regard to the modality shift effect. Therefore only the crossover effect represents a vulnerability marker for schizophrenia. Correlations between the modality shift and the crossover effect revealed strong correlations in the schizophrenic group only.

Adolescent↗
PubMed1992

Neuropsychological indicators of the vulnerability to schizophrenia.

Schizophrenia is associated with enduring deficits in neuropsychological functioning. It is widely undecided if the various aspects of neuropsychological impairment are a consequence of the disorder or if they are also present premorbidly and in populations at increased risk for schizophrenia (vulnerability markers). Neuropsychological deficits in healthy relatives of schizophrenic patients who are at an elevated risk for schizophrenia and who did not yet pass the period of risk would indicate that these deficits are vulnerability markers. This hypothesis was tested for three neuropsychological paradigms which have been proven to distinguish schizophrenic patients from controls. 33 siblings of drug-free schizophrenic probands revealed deficits has compared to 33 matched healthy controls in a blurred single target version of the Continuous Performance Test and in a multiple item version of the Span of Apprehension Test but not so in less difficult versions of both tests or in the time needed to react to stimuli with shifting modality.

Adult↗
PubMed1988

Placebo injections and surveillance of alcohol intake during inpatient treatment of female alcoholics.

Institutions for treating alcoholics differ widely with respect to how restrictively they apply psychopharmacological agents and how rigorously they control patients for intake of alcohol. This study investigates the impact of such policies on relapse rates. During a three month inpatient treatment, 70 female alcoholics were assigned to one of four conditions: (a) strict surveillance of alcohol intake by means of breath tests and frequent checks of patient's rooms as well as injections of a placebo purportedly reducing craving, (b) no surveillance but placebo injections, (c) surveillance but no placebo injections, and (d) neither surveillance nor placebo injections. The amount of surveillance did not influence relapse rates. However, during inpatient treatment more relapses occurred among patients who received the placebo injections than among those who did not. Although this effect was no longer significant following treatment, the increase of relapse rates suggests caution in the application of nonspecific medication in the treatment of alcoholics.

Adult↗
PubMed1986

The patient rejection scale: cross-cultural consistency.

The Patient Rejection Scale, which was developed to assess rejecting feelings of family members toward mental patients, was administered to a sample of 80 relatives living with schizophrenic patients in the Federal Republic of Germany. In spite of the cross-cultural differences involved, the response distributions of the German sample and a New York City sample of families were almost identical. The findings are discussed in the context of "expressed emotions" research.

Adolescent↗
PubMed1983

Self assessment of relapse risk and assertiveness in relation to treatment outcome of female alcoholics.

Prior to and following social-skills training during a three months inpatient treatment, 145 female alcoholics indicated for various situations involving social pressure to drink alcohol (a) how difficult it would be for them not to drink (Relapse Risk) and (b) the degree of discomfort they expected (Specific Assertiveness). In addition, General Assertiveness situations, not related to alcohol, were evaluated. Patients who relapsed three months after treatment evaluated the situations more difficult to deal with and creating more discomfort than abstaining patients, although the groups did not differ in their self-rated assertiveness in non-alcohol-related situations. All ratings improved throughout the training, but the differences between outcome groups were similar before and after. When patients were excluded who had relapsed already during treatment, Relapse Risk but not Specific Assertiveness still discriminated between outcome groups. The prognostic power of the Risk rating seems to reflect a general efficacy expectation evident in a strong relation to patients' conviction of being able to stay abstinent, stated already at admission.

Alcoholism↗
PubMed1983

Self assessment of social competence in situations with and without alcohol by female alcoholics in treatment.

Female alcoholic in-patients (N = 156) were asked during a three months treatment to rate the degree of discomfort they expected (a) in situations demanding assertiveness, but not involving rejection of alcoholic beverages and (b) in situations characterized by social temptation to drink. Correlations of ratings with age, duration of problem drinking, mean ethanol consumption per day or length of education were insignificant. Actual experience with social temptation situations in the past did not influence the rating. A principal Component Analysis showed that ratings of discomfort in general social situations and in alcohol related social situations are largely unrelated. The result of partially independent appraisals of general and alcohol related assertiveness suggests that both should be assessed independently, and generalizations from one to the other might be misleading.

Adult↗
PubMed1980

Loudness judgments, evoked potentials, and reaction time to acoustic stimuli early and late in the cardiac cycle in chronic schizophrenics.

Two experiments were performed to test Broen's (1968) theory that chronic schizophrenics show increased sensitivity of the inhibitory mechanisms assumed to follow cardiovascular baroreceptor stimulation. Subjects were chronic schizophrenics and normals matched for age and education. In Experiment I reaction times, vertex potentials, and loudness judgments to single tones presented during systole or diastole were analyzed. Contrary to expectation, schizophrenics more often judged tones presented during systole to be louder than tones presented during diastole; the opposite was true for normals. A similar pattern was found in Experiment II, where pairs of tones were presented instead of single tones. No influence of cardiac cycle on reacion time or evoked potentials emerged. Results do not support Broen's assumption.

Acoustic Stimulation↗
PubMed1977

[An alcohol contact program: training for increased security of alcoholics in trial situations].

Alcoholics who have taken the decision to abstain are known to develop, partially out of fear of a relapse, an almost phobic avoidance behaviour towards situations where alcoholic drinks may be proffered. Starting from this observation a four-hour behavioural programme, involving modeling and the discussion of appropriate behaviour, was developed to prepare patients for such situations. The two methods resulted in equally highly significant improvement, as measured both by self-assessment and by the assessment of independent observers.

Alcoholism↗