Enhancing challenged students' recognition of mathematical relations through differential outcomes training

Previous studies have reported that the differential outcomes procedure enhances learning and memory in special populations with cognitive deficits (see Goeters, Blakely, & Poling, 1992, for a review). In the present study we extend these findings to healthy adults who were asked to discriminate between the symbols " > " and " < " in mathematical statements. In Experiment 1, the performance of participants who showed difficulties in discriminating between these symbols was better (shorter response times) for the differential outcomes condition than for the nondifferential outcomes condition. In Experiment 2, the difficulty of the task was increased by using signed decimal numbers. Similar to Experiment 1, participants who initially had difficulties in discriminating between the symbols showed better performance (higher accuracy) for the differential outcomes condition than for the nondifferential outcomes condition, but only when both numbers were negative. These findings suggest that the differential outcomes procedure can be used to improve performance of challenged healthy adults on discrimination tasks with mathematical symbols and relations.     

Differential age effects on attention-based inhibition: inhibitory tagging and inhibition of return

The purpose of this study was to determine whether 2 forms of attentional inhibition, inhibition of return (IOR) and inhibitory tagging, are differentially affected by the aging process. The authors tested 24 younger adults (mean age = 22 years) and 24 older adults (mean age = 69 years) on a combined IOR and Stroop task (Vivas & Fuentes, 2001). As predicted, younger adults' performance was consistent with inhibitory tagging of objects at inhibited locations. Although older adults demonstrated intact IOR, there was no evidence of inhibitory tagging. The results suggest that age deficits in inhibition are selective.     

Stroop interference is affected in inhibition of return

In previous research, we have shown that the processing of targets that are presented to locations subject to inhibition of return (IOR) is affected by an inhibitory tagging mechanism. This mechanism acts by disconnecting activated representations of stimuli at inhibited locations from their associated responses. In two experiments, we assessed whether this inhibitory tagging mechanism of visual attention is also applied to task-irrelevant but prepotent dimensions of target stimuli, such as words in the Stroop task. To test this hypothesis, we examined the Stroop effect in an IOR procedure. The results showed that (1) IOR can be found in a color discrimination task, (2) the Stroop interference was reduced (Experiment 1) or eliminated (Experiment 2) when stimuli appeared at cued locations, as compared with cases in which they were presented at uncued locations, and (3) the effect of inhibitory tagging was limited to the shortest stimulus onset asynchrony value, replicating previous findings. These results agree with the idea that inhibitory tagging, occurring in IOR, affects the efficiency with which color words compete for responses in Stroop-like situations.     

The global precedence effect is not affected in inhibition of return

This study assessed whether inhibitory processes occurring in IOR affect perceptual processing of hierarchically organised stimuli. Experiment 1 used a global/local task that presented stimuli to the left or the right side. Results showed a global task advantage and a larger interference in the local than in the global task—the global precedence effect (GPE). These effects were larger than in previous studies using centrally presented stimuli, which suggests a greater involvement of low spatial frequency analysis with peripheral than with central stimuli. Experiment 2 combined the global/local task with IOR. Results replicated those of Experiment 1 but there was no interaction with stimulus location. That is, the GPE was not affected in IOR. Thus, we conclude that the GPE and inhibitory processing occurring in IOR are subserved by different mechanisms.