Table 2 Retrieval practice in schizophrenia: previous results

AhnAllen et al. (2007)

18 right-handed male patients with schizophrenia

Mean age = 42.59 years, Mean length of illness = 18.5 years, Mean chlorpromazine equivalent = 422.53 mg

18 right-handed male healthy controls

RIF: 2 (associative strength: strong, weak)*3 (learning condition: RP+, RP-, NRP)

Patients with schizophrenia recalled fewer category-exemplar pairs (M = 33.92, SD = 15.66) than did normal controls (M = 50.48, SD = 14.41). Significant effect for group (ANCOVA), F (1, 34) = 12.64, p = .001, item, F (2, 33) = 35.42, p < .001, and associative strength, F (1, 34) = 30.86, p < .001.

Allen et al. (2003)

10 patients with schizophrenia

10 HC

2 (associative strength: strong, weak)*3 (learning condition: RP+, RP-, NRP)

Control subjects displayed similar patterns of retrieval practice (RP+ > NRP > RP-) for both strong and weak categories, though

schizophrenic subjects showed evidence of a disproportionate drop

in recall for RP+ weak categories-exemplar pairs in relation to their

close to normal recall for RP+ strong categories-exemplar pairs

Nestor et al. (2005)

17 right-handed male patients with schizophrenia

Mean age = 45.53 years, Mean length of illness = 21.27 years, Mean chlorpromazine equivalent = 331 mg

18 right-handed male HC

RIF: 3 (learning condition: RP+, RP-, NRP)

The control group had mean recall rates of 72.78% (SD = 18.98) for RP+ items, 39.52% (SD = 20.30) for RP- items, and 46.84% (SD = 12.61) for NRP items. The patient group had mean recall rates of 49.37% (SD = 19.98) for RP+ items, 21.41% (SD = 19.40) for RP- items, and 27.68% (SD = 11.42) for NRP items. ANCOVA yielded a significant effect for group, F = 11.038, (1, 28), p <  0.01

For the initial category-word stem completion task of retrieval practice, controls completed 86.9% (SD = 12.71) of the stems versus 75.89% (SD = 16.49) for patients with schizophrenia.

Soriano et al. (2010)

30 outpatients with schizophrenia

Gender (m/f) = 26/4

Mean age = 39.17 years, Mean length of illness = 16.3 years, Mean chlorpromazine equivalent unknown.

18 HC, Gender (m/f) = 8/12

RIF: 3 (learning condition: RP+, RP-, NRP)

The facilitation effect of practice was significant for patients, F(1.29) = 68.15, MSE = 11,179.45, p < .05, ω² = .7 with participants recalling more RP+ than NRP items. The percentage of correct recall in the retrieval practice phase was 73.9 for the schizophrenic group, and 75.1 for the control group.