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Schizophrenia impairs both facial emotion processing and sustained attention. Through separate studies, it is known that the presence of a task-irrelevant facial stimulus disproportionately interferes with performance, whereas increasing the salience of task stimulus improves performance during a sustained attention task in patients with schizophrenia. We wished to investigate a potential interaction effect of background facial emotion expression (black and white happy faces vs. grey oval) and target stimulus salience (bright white vs. grey) using the Continuous Performance Test-Identical Pairs version (CPT-IP) in patients with schizophrenia. Thirty-six patients with schizophrenia and 28 healthy control subjects completed 4 different versions of the CPT-IP. We found that healthy controls exhibited higher signal detection sensitivity (d′) when salient target stimuli were presented on the facial background than when the same stimuli were presented on the grey-oval background. By contrast, patients were not affected by background stimuli when target number stimuli were salient. When target number stimuli were not salient, both patients and controls showed higher d′ in the grey-oval background condition compared with the facial background condition. This study highlight the significance of stimulus salience during CPT-IP in schizophrenia as background stimuli did not produce a differential effect on performance. Our results suggest that, in the situations where facial emotion stimuli are present, patients' sustained attention can be deteriorated and that the use of salient materials is important in improving performance in schizophrenia.

Patients with schizophrenia have difficulty recognising the emotion that corresponds to a given facial expression. According to signal detection theory, two separate processes are involved in facial emotion perception: a sensory process (measured by sensitivity which is the ability to distinguish one facial emotion from another facial emotion) and a cognitive decision process (measured by response criterion which is the tendency to judge a facial emotion as a particular emotion). It is uncertain whether facial emotion recognition deficits in schizophrenia are primarily due to impaired sensitivity or response bias. In this study, we hypothesised that individuals with schizophrenia would have both diminished sensitivity and different response criteria in facial emotion recognition across different emotions compared with healthy controls. Twenty-five individuals with a DSM-IV diagnosis of schizophrenia were compared with age and IQ matched healthy controls. Participants performed a "yes-no" task by indicating whether the 88 Ekman faces shown briefly expressed one of the target emotions in three randomly ordered runs (happy, sad and fear). Sensitivity and response criteria for facial emotion recognition was calculated as d-prime and In(beta) respectively using signal detection theory. Patients with schizophrenia showed diminished sensitivity (d-prime) in recognising happy faces, but not faces that expressed fear or sadness. By contrast, patients exhibited a significantly less strict response criteria (In(beta)) in recognising fearful and sad faces. Our results suggest that patients with schizophrenia have a specific deficit in recognising happy faces, whereas they were more inclined to attribute any facial emotion as fearful or sad.