Proactive interference in the retention of “attentional sets” in pigeons

In Experiment 1, six groups of pigeons (n=8) were tested for wavelength generalization either immediately or 24 h after learning a successive discrimination, with 550 nm reinforced and a black vertical line extinguished. The groups differed in the stimulus present during single stimulus pretraining, which was 550 nm (pretrain S+), the vertical Une (pretrain S?), or a neutral dim white light (pretrain Sn), respectively. The three immediate generalization gradients were steep and indistinguishable, reflecting only the immediately preceding discrimination training condition. The three delay gradients were flatter, with the flattening particularly marked in the pretrain S? group. This was interpreted as proactive interference (PI) resulting from the memory that both the 550-nm and the line stimuli had previously been reinforced. In Experiment 2, two (TD) groups of pigeons (n=16) were given single stimulus training with a 555-nm keylight followed by eight sessions of discrimination training with two line angles, then one session of non-differential (ND) training with the same two lines, and then a wavelength generalization test either immediately or after a 24-h delay. Two other (hold) groups (n=16) received similar training, except for the TD Une angle training sessions, in these hold groups, the wavelength gradient was flatter in a delayed test; in the TD groups it was steeper, indicating PI from the prior TD training. These two experiments suggest that the “attentional sets,” which purportedly result from TD and ND training, may fruitfully be viewed as target memories subject to the principles of interference theory.     

Statistical and individual temporal stability of the WISC-R for cognitively disabled adolescents

This study examines the temporal stability of the WISC-R for 155 13-and 14-year-old adolescents identified as either EMR or LD who were involved in special education during the preceding three-year time period. The three major scales of the WISC-R were found to be more stable over a three-year period for the LD than for the EMR group, while the subtest scales for the EMR group, showed greater stability over the three-year interval. Test-retest coefficients for the EMR group were substantially lower than those presented in the WISC-R test manual. A large proportion of individuals within both groups showed statistically significant differences on one or more of the IQ score scales between testings based on standard errors of measurement. These findings are examined in relation to individual placement of students, reporting confidence intervals in reports, and calculation of the best unbiased estimate of intellectual functioning.