Raymond E. Sanders’s research while affiliated with University of Akron and other places

Previous investigations of adult age differences in the redundant signals effect suggest that both older and younger adults benefit from the presentation of redundant information. However, age deficits in divided attention may cause older adults to process redundant information in a different manner. In the present experiment, we tested between two competing explanations for the redundant signals effect: separate activation and coactivation. To investigate this issue, we used a bimodal detection task in which the auditory signal was a 1000-Hz tone and the visual signal was an asterisk. Both age groups showed significant violations of Miller's race model inequality, providing evidence for coactivation. These results suggest that, despite age-related deficits in divided attention, the ability to coactivate information from bimodal signals is spared with increased age.

Episodic or context dependent memory is often studied as a function of the context cues in immediate retrieval of target information. Little research has been done on how the relationship of context cues to target retrieval changes over time, and none with older adult subjects. The current research investigated how the influence of context on accuracy of memory changes over time, and age-related differences in those influences. Using immediate, 2- and 7-day retention intervals, our results indicate that, while context initially supports the retrieval of information, assistance is temporary and fades before the memory for the target information. These changes in context effects were not different for younger and older adult groups.

We compared the multiplication verification and production performances of healthy younger (n = 20) and older (n = 20) adults to that of mildly demented (Mini Mental Status Exam range: 19–27) individuals diagnosed with probable Alzheimer's disease (n = 18). While healthy older adults and Alzheimer's patients were slower than younger adults, the older adults actually showed significantly smaller problem-size effects for verification and production reaction time (RT) tasks. These results suggest that retrieval of multiplication fact knowledge from long-term memory for multiplicands greater than zero remains largely intact in mildly demented individuals diagnosed with probable Alzheimer's discase, although these individuals may have more difficulty with volitional retrieval because group differences were larger for some production analyses (require volitional retrieval) than for verification analyses (simply requires familiarity). However, for problems involving zero multiplicands (but not 1’s), healthy older adults and especially Alzheimer's patients showed significantly higher error rates than younger adults, suggesting that rule retrieval of correct solutions in memory was impaired in both of these older groups for problems involving zero operands. Also, when RT was regressed on problem size across groups, there was no effect for problem size for the production task for Alzheimer's patients—but there was for healthy younger and older adults. Finally, when verifying problems, there was a significant problem size effect of comparable magnitude for all three groups.

Making training easy and rapid has been a goal for those who train older learners. Even though they may initially produce easy and rapid performance change, however, some training conditions may actually hinder learning by reducing subsequent retention and generalization (Schmidt & Bjork, 1992). To assess this, older and younger adults were trained on an algorithm for mentally squaring two-digit numbers. Half of our participants received training in a high-variability content condition involving problems widely dispersed across the range of decade and 1's digits of two-digit numbers; the other participants were in the low- variability content condition that involved training problems with a narrow range. For both age groups, high- variability training resulted in inferior performance at the end of training, compared to low-variability training. Consistent with Schmidt and Bjork, however, high-variability trained younger adults were marginally better at retention, and were significantly better on nontrained transfer problems. In contrast, high-variability trained older adults did not differ from their low-variability trained agemates at either retention or generalization.

Two psychological refractory period (PRP) experiments were conducted to examine overlapping processing in younger and older adults. A shape discrimination task (triangle or rectangle) for Task 1 (T1) and a lexical-decision task (word or nonword) for Task 2 (T2) were used. PRP effects, response time for T2 increasing as stimulus onset synchrony (SOA) decreased, were obtained for both age groups. The effect of word frequency on T2 was smaller at the short SOA than at the long SOA, reflecting slack effects, which were larger for older than younger adults in both experiments. These results suggest that older adults can perform lexical access of T2 in parallel with the processing of T1 at least as efficiently as younger adults.

Two psychological refractory period (PRP) experiments were conducted to examine overlapping processing in younger and older adults. A shape discrimination task (triangle or rectangle) for Task 1 (T-1) and a lexical-decision task (word or nonword) for Task 2 (T-2) were used. PRP effects, response time for T-2 increasing as stimulus onset synchrony (SOA) decreased, were obtained for both age groups. The effect of word frequency on T-2 was smaller at the short SOA than at the long SOA, reflecting slack effects, which were larger for older than younger adults in both experiments. These results suggest that older adults can perform lexical access of T-2 in parallel with the processing of T-1 at least as efficiently as younger adults.

Several theories have suggested that age-related declines in cognitive processing are due to a pervasive unitary mechanism, such as a decline in processing speed. Structural equation model tests have shown some support for such common factor explanations. These results, however, may not be as conclusive as previously claimed. A further analysis of 4 cross-sectional data sets described in Salthouse, Hambrick, and McGuthry (1998) and Salthouse and Czaja (2000) found that although the best fitting model included a common factor in 3 of the data sets, additional direct age paths were significant, indicating the presence of specific age effects. For the remaining data set, a factor-specific model fit at least as well as the best fitting common factor model. Three simulated data sets with known structure were then tested with a sequence of structural equation models. Common factor models could not always be falsified--even when they were false. In contrast, factor-specific models were more easily falsified when the true model included a unitary common factor. These results suggest that it is premature to conclude that all age-related cognitive declines are due to a single mechanism. Common factor models may be particularly difficult to falsify with current analytic procedures.

Several theories have suggested that age-related declines in cognitive processing are due to a pervasive unitary mechanism, such as a decline in processing speed. Structural equation model tests have shown some support for such common factor explanations. These results, however, may not be as conclusive as previously claimed. A further analysis of 4 cross-sectional data sets described in Salthouse, Hambrick, and McGuthry (1998) and Salthouse and Czaja (2000) found that although the best fitting model included a common factor in 3 of the data sets, additional direct age paths were significant, indicating the presence of specific age effects. For the remaining data set, a factor-specific model fit at least as well as the best fitting common factor model. Three simulated data sets with known structure were then tested with a sequence of structural equation models. Common factor models could not always be falsified-even when they were false. In contrast, factor-specific models were more easily falsified when the true model included a unitary common factor. These results suggest that it is premature to conclude that all age-related cognitive declines are due to a single mechanism. Common factor models may be particularly difficult to falsify with current analytic procedures.

We built Deese (1959)/Roediger and McDermott (1995) (DRM) false memory lists composed of multiplication problems rather than words. Half these lists contained table-related, near neighbors (e.g., 3 x 7 = ??, 3 x 9 = ??) of a missing multiplication answer lure (e.g., 24). The other half contained problems unrelated to the lure (e.g., 5 x 5 = ??, 11 x 3 = ??). Participants solved each problem in a single list and then took immediate recognition (Experiment 1) or recall and then recognition tests (Experiment 2) for the answers. Many people misremembered that the lure was an answer to a study-phase problem, but only when solving the study list that contained the lure's neighbors. False memory was also greater for some list-lure combinations than others, as seen previously with words. We have thus demonstrated that numbers can also produce false memory, and we use the mental math and DRM task literatures to explain these results.

This experiment had two purposes: investigation of the effect of variability in the content used during training on concept learning, retention, and transfer and the extent to which this training manipulation interacts with age. Participants were 27 older adults (M = 68.2 yr., SD = 7.4) and 54 younger adults (M = 20.6 yr., SD = 4.0) who were asked to learn an imaginary disease by reviewing the symptoms of fictional patients. Participants were assigned to one of two variability groups in training, which were defined by how much patient cases resembled each other. Dependent measures were classification accuracy over eight blocks of training, followed by retention and transfer ("diagnosing new patients") two days later. Analysis of variance yielded only one significant interaction of age and training variability (on retention), but none of the paired comparisons were significantly different. There were no main effects of training group on any dependent variable.