Test-retest gains in WAIS scores after four retest intervals

Administered the WAIS to 76 male college students on two occasions with a retest interval of either 1 week, 1 month, 2 months, or 4 months. Essentially all Verbal, Performance, and Full Scale IQs increased significantly on the retest. Increases in Verbal IQ for the four time intervals were 4.7, 1.8, 2.3, and .8 IQ points, respectively; the latter was the only nonsignificant gain found. The Performance IQ increased by 11.4, 9.8, 8.7, and 8.0 points for each subsequent time period, and the Full Scale IQ increased by 8.0, 5.7, 5.4, and 4.2 points for each respective time period. Test-retest correlations for the four intervals ranged from .91 to .72 for the Verbal IQ, .87 to .79 for the Performance IQ, and .94 to .74 for the Full Scale IQ. The results were pitted against similar test-retest studies, and clinical and research implications were discussed.