The Effect of Previous Preparatory Intervals Upon Anticipatory Responses in the Reaction Time of Schizophrenic and Nonschizophrenic Patients

Reaction Time and Attention in Schizophrenia: A Critical Evaluation of the Data and Theories*

“…0 1 ) . Unfortunately this investigation differs in several ways from the Nideffer et al (19716) study, so their divergent findings may be explained in more than one way. Specifically, Nideffer et al (19716) compare schizophrenic patients with nonschizophrenic psychiatric patients rather than normal controls.…”

“…Unfortunately this investigation differs in several ways from the Nideffer et al (19716) study, so their divergent findings may be explained in more than one way. Specifically, Nideffer et al (19716) compare schizophrenic patients with nonschizophrenic psychiatric patients rather than normal controls. The significance of the PPI > PI relationship (with PI controlled) might be attenuated by a greater tendency for nonschizophrenic patients than for normals to respond slowly in this situation.…”

“…While the Nideffer et al (1971a) study also found a nonsignificant PPI effect when PI was controlled, it is unable to resolve the contribution of these two factors. It did involve a comparison of schizophrenics and normals, like the study of Zahn (1970), but the Pis were restricted to 0.4, 1.0, and 2.0 seconds.…”

“…Two recent studies have suggested that an important addition to earlier findings of PPI effects needs to be made. Nideffer et al (1971a and 19716) Moreover, when anticipatory responses (those preceding stimulus presentation) were considered, schizophrenics were found to show significantly more than nonschizophrenics both when PI was 8 seconds and when P P K P I . Since the 8-second PI was the longest used, these two conditions can probably be best summarized by the PPI < PI categorization.…”

“…A direct comparison of the PPI > PI retarding phenomenon for schizophrenics, nonschizophrenic psychiatric patients, and normal controls with an adequate range of Pis would best decide this issue. Even in its absence, however, the Nideffer et al (19716) explanation must be questioned on logical grounds. These authors suggest that the presumed greater PPI > PI effect in schizophrenics "may be primarily because they are debilitated by short Pi's rather than because the short Pi's were preceded by long ones" (p. 365).…”