Martin D. Murphy’s research while affiliated with University of Akron and other places

Background/Study Context: This study examined the potential impact of self-reported depressive symptoms on the age-related capacity for inhibition and suppression, utilizing a negative priming paradigm. Methods: One hundred eighty-five community-residing adults varying in age (98 younger adults, Mage = 22; 87 older adults, Mage = 69) completed a nonconscious priming task, the Geriatric Depression Scale (GDS), the White Bear Suppression Inventory (WBSI), the Depression Sensitivity Scale (DSS), a free thought suppression task, as well as several measures indexing overall cognitive ability and psychomotor speed. Hierarchical regressions investigated the interaction of depressive symptoms with age and its effect on both positive and negative priming performance, indexing both facilitation and inhibition effects, respectively. Results: Results support the hypothesis that noncognitive factors affect effortful performance among older adults, although this influence varied with the specific component of the GDS, i.e., Dysphoria, Social Withdrawal, and Cognitive Control, and with the measure of depressive symptoms, i.e., GDS versus DSS. Conclusion: These data suggest that aging’s impact on both facilitation and inhibition, e.g., positive and negative priming, are to an extent, a function of individual differences in depressive symptoms that interact with age in influencing the necessity to reallocate one’s cognitive resources to deal with depressive thoughts and feelings.

Both researchers and practitioners need to know more about how laboratory treatment protocols translate to real-world practice settings and how clinical innovations can be systematically tested and communicated to a skeptical scientific community. The single-case time-series study is well suited to opening a productive discourse between practice and laboratory. The appeal of case-based time-series studies, with multiple observations both before and after treatment, is that they enrich our design palette by providing the discipline another way to expand its empirical reach to practice settings and its subject matter to the contingencies of individual change. This article is a user's guide to conducting empirically respectable case-based time-series studies in a clinical practice or laboratory setting.

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.

The authors report a lexical decision experiment designed to determine whether activation is the locus of the word-frequency effect. K. R. Paap and L. S. Johansen (1994) reported that word frequency did not affect lexical decisions when exposure durations were brief; they accounted for this by proposing that data-limited conditions prevented late-occurring verification processes. Subsequently, P. A. Allen, A. F. Smith, M. Lien, T. A. Weber, and D. J. Madden (1997) and K. R. Paap, L. S. Johansen, E. Chun, and P. Vonnahme (2000) reported additional evidence that word-frequency effects do and do not have an activation locus, respectively. The authors further tested this issue in a lexical decision experiment using data-limited procedures--predicted by verification models to eliminate word-frequency effects. The authors observed word-frequency effects using individually determined exposure durations that were only 1 screen cycle longer than the exposure duration that yielded chance performance. Word-frequency effects persisted even when an adjusted measure of performance was used.

In this project we examined the effect of adult age on visual word recognition by using combined reaction time (RT) and accuracy methods based on the Hick-Hyman law. This was necessary because separate Brinley analyses of RT and errors resulted in contradicting results. We report the results of a lexical decision task experiment (with 96 younger adults and 97 older adults). We transformed the error data into entropy and then predicted RT by using entropy values separately for exposure duration (thought to influence peripheral processes) and word frequency (thought to influence central processes). For exposure duration, the entropy-RT functions indicate that older adults show higher intercepts and slopes than do younger adults, suggesting an encoding decrement for older adults. However, for word frequency, older adults show higher intercepts but not steeper slopes than younger adults. Older adults thus show a peripheral processing decrement but not a central processing decrement for lexical decision.

There has been a resurgence of interest in single-subject research designs and analytic tools to help clinicians detect treatment effects. The present study investigates Nugent's (2000) visual analysis procedures, which were designed to aid practitioners in detecting clinical change for the purposes of practice evaluation. The ability of the visual procedures to detect real change in short auto-correlated data streams and the ability of the procedures to help clinicians discern cases when no actual change has occurred were evaluated. Monte Carlo analyses indicate that the power of the visual procedures is acceptable for effect sizes of 2.25 or greater when there are at least 14 data points (7 baseline and 7 treatment) in the data set. The procedures, however, frequently lead to erroneous decisions that effects are present in data streams when, in fact, there are none. The mean type I error rate across various N' s and levels of auto-correlation was .66. As they are currently designed, Nugent's visual analysis procedures make too many type I errors to be useful. (PsycINFO Database Record (c) 2012 APA, all rights reserved)

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.

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.