The name is absent

Conditioned Blocking: Schizophrenia

with∕without flanking letters. The distractors increased response times in controls and
chronic schizophrenics but not the acutely ill; but an interaction with response made
interpretation difficult. The second report using a complex audiovisual learning test con-
firmed an attenuation of CB in the acutely ill. Again the effect was stronger with increased
symptom severity but it was confounded by a learning floor effect in the chronic patients.

We developed a Visuospatial CB task-form (Oades et al., 1996) in which we compare the
relationship of CB to personality, the types of symptom and their severity (correlational
and subgroup analysis). Learning measures were also studied to try to discern if the type
of task-solving strategy used related to CB. Pertinent here are reports that subjects with an
outgoing personality perform better in situations requiring parallel processing (Eysenck,
1982, pp. 128-129), likely in this form of CB, and they may show quantitative differences
of monoamine metabolism (e.g. low 5HT activity: Linnoila et al., 1983; Schalling et al.,
1984). Hence the relationship of performance to medication and the status of monoamine
metabolism (urine samples) was studied. Thus, high levels of 5HT metabolism might be
expected to interfere with CB, but the relationship of catecholamine metabolism to CB is
less easy to predict. An increase of DA metabolism might be expected to be beneficial in
healthy subjects on the basis of metabolite increases and improved learned inattention
following neuroleptic treatment of animals. However, patient responses may differ in view
of illness-related differences in DA and NA activity and medication response. An initial
report found CB attenuated in young NP rather than PH schizophrenics and to be associated
with increased DA utilization (Oades et al., 1992).

The question of specificity was approached by including OCD patients. The OCD-
psychosis comparison is of interest because of the implication of related frontal pathology
(e.g. orbito-frontal vs prefrontal) and monoaminergic dysfunction (5HT vs DA) in both
groups: they both show impaired attention-related information processing (reviews in Reed,
1985; Insel, 1992; Straube & Oades, 1992) and psychosis not infrequently develops through
an obsessive phase in adolescence (Eggers, 1968; Eisen & Rasmussen, 1993).

Methods

Subjects

From 30 consecutive admissions for schizophrenia-like psychosis (SCH), 26 in-patients
learned the CB task; three did not achieve the learning criterion and the data for another
were lost. Diagnosis (DSM-III-R) was made by the senior therapist, two psychologists and
a clinician who also rated a semi-structured interview on tape. Diagnostic subtypes included:
12 paranoid (295.3), four disorganized (295.1), two undifferentiated (295.9), one residual
(295.6), four schizoaffective (295.7), two reactive (298.8) and one atypical (298.9). Further
diagnoses were not made. Exclusion criteria included other major illnesses, substance abuse
and a performance IQ under 70 (Ravens standard progressive matrices, Table 1).

Psychotic patients were interviewed for the assessment of positive and negative symptoms
over the week of the tests (Andreasen, 1983, 1984: for four raters and all 64 questions,
Spearman p ranged from .64 to .75 between subjects). A subgroup of paranoid-hal-
lucinatory patients (PH) was separated on a median split (score of 7) on the scores for
delusions and hallucinations from the remaining non-paranoid group (NP). (Group num-

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