Impaired spatial working memory maintenance in schizophrenia involves both spatial coordinates and spatial reference frames

Spatial working memory (SWM) dysfunction is a central finding in schizophrenia; however, more evidence of impaired maintenance over time is required. Consequently, the present study examined SWM maintenance over short unfilled delays, and with encoding equated. The influence of a vertical reference frame to support maintenance was also investigated. The performance of 58 patients with schizophrenia and 50 healthy controls was assessed using the Visuo-Spatial Working Memory (VSWM) Test across three unfilled delays (0, 2, and 4 s). Inaccuracy of direction and distance responses was examined at each delay duration. The results showed that performance was significantly less accurate for both distance and direction responses at 2 and 4 s delays in schizophrenia, but was not significantly different from controls at the 0 s delay. Patients showed a particularly marked loss of accuracy between the time interval of 0–2 s. Furthermore, schizophrenia participants exhibited significantly greater response variability at the vertical axis of symmetry than controls at the 2 and 4 s delays, but not at the 0 s delay. These data clearly show both impaired maintenance over time and difficulty using a vertical frame of reference in schizophrenia. The latter findings may reflect, in part, dysfunctional reference-related inhibition.