Dichotic monitoring and focused versus divided attention in schizophrenia

Abstract

The target detection performance of normals, chronic schizophrenics with positive symptoms and those with negative symptoms was compared in focused and divided attention conditions. The focused condition involved the monitoring of one, and the divided condition the monitoring ofboth, ofthe dichotically presented word lists. The amount and rate of list presentations were held constant across the conditions in an attempt to separate attentional from difficulty and capacity factors. Results showed that while the overall performance of both schizophrenic groups was lower than that of the normals, their performance change from the focused to the divided attention condition did not differ from that ofthe normals. These results do not support a schizophrenic selective attention deficit hypothesis.The concept selective attention denotes the voluntary control over the direction of attention, and schizophrenics have long been characterized as deviant in this respect. Kraepelin (1919) noted that some patients showed a kind of irresistible attraction of attention to casual external impressions. With McGhie &Chapman's (1961) report of the subjective experiences of newly admitted schizophrenics' inability to organize selectively and control incoming information, the selective attention hypothesis, which views the schizophrenic as the passive victim of irrelevant and distracting information, became the dominant paradigm.which assume that some selection defect is present in schizophrenia. Early models assumed faulty sensory selection, but more recent models specify more precisely that the faulty selection device is that operating after sensory analysis has been adequately carried out, e.g. Frith (1979) and Hemsley & Richardson (1980). Experimental studies have offered varying and inconclusive evidence, and it is far from clear that there is a schizophrenic-specific selective attention deficit at any level. Digit recall tasks and shadowing tasks have been widely used for manipulating the presence-absence of distractors. Generally these try to show a differential schizophrenic-normal fall in performance with the introduction of distraction.Based on McGhie's reports and similar evidence, many models have been devised Digit recall tasksLawson et al. (1967) showed that while schizophrenic performance was worse than that of normals, the magnitude of this difference increased in the distraction condition. However, Berg & LeventhaI(l977) among others found that while schizophrenics performed worse than a group of non-schizophrenic psychotic controls, distraction did not produce a . differential effect. Hemsley & Zawada (1976), using a pre-and post-instruction procedure, found that while normals benefited from pre-instruction, both schizophrenics and depressives did not, and therefore exhibited susceptibility to distraction. Oltmanns et al. (1978) found in one study that schizophrenics were more impaired in the distraction condition than psychiatric controls, but only for long subtasks. In another study they found this kind ofdifferen...

Interhemispheric coordination and focused attention in chronic and acute schizophrenia

“…Acute schizophrenics, who are unable to do this, therefore show impaired binaural scores. The fact that, as Allen's (1982) data show, chronic schizophrenics have little difficulty in focusing attention on one ear explains why their binaural deficit was not significant in Green et al 3 (1983) study and disappeared altogether in the present story comprehension experiment.…”

“…The acute schizophrenics in this study performed differently from the chronic patients of Allen (1982) in not deriving any advantage from knowledge of which ear received the targets in the focused attention condition. It appears that acute schizophrenics cannot focus attention on one ear only in the presence of competing input from the other, whereas no such problem exists for chronics.…”

“…The stimulus lists have been described in detail by Allen (1982). The focused attention condition comprised 200 non-target words to be presented to the non-monitored ear and 168 non-target words plus 32 target words (16 'dog' and 16 'lion') to be presented to the monitored ear.…”

Reducing persistent auditory hallucinations by wearing an ear‐plug

“…These were respectively : (1) audiometric pure-tone thresholds at differing frequencies for each ear; (2) shadowing monaural and dichotic word lists for a target (Allen, 1982); (3) monaural and binaural speech comprehension (Green & Kotenko, 1980). The patient (B. C.) was a 42-year-old chronic schizophrenic with a 22-year history of psychosis.…”

The Core of Negative Symptoms in Schizophrenia: Affect or Cognitive Deficiency?

“…Allen [36] found no evidence of attentional or cognitive impair ment in schizophrenics with negative symp tomatology in comparison to other patients. In the study of Green and Walker [37] posi tive rather than negative schizophrenics showed significant deficits on a digit-span task when compared with normal subjects.…”