Martin D. Murphy

Clinical Practice as Natural Laboratory for Psychotherapy Research: A Guide to Case-Based Time-Series Analysis.

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 users guide to conducting empirically respectable case-based time-series studies in a clinical practice or laboratory setting.

Age differences in overlapping-task performance: Evidence for efficient parallel processing in older 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 (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.

Metamemory in older adults: the role of monitoring in serial recall.

Older and younger adults were asked to think aloud while studying sets of pictures matched in difficulty for immediate serial recall. When instructed only to remember, young adults tended to study longer, rehearse more, and recall better than did older adults on the most difficult lists. Young adults were also much more likely to spontaneously test themselves during study in the most difficult condition. Older adult groups instructed either to study longer or to self-test, both showed improved recall. Only the older adults who had been instructed to self-monitor, however, recalled better on tests of short-term maintenance and generalization; overt rehearsal data showed that these older adults continued to test themselves. Metamemory deficits may be present with older adults when a strategy, like self-testing, is needed to generate metamemorial knowledge. Strategies such as self-testing can be easily taught, however, and they hold promise of being useful across situations.

How Shared Are Age-Related Influences on Cognitive and Noncognitive Variables?

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.

Evidence for an activation locus of the word-frequency effect in lexical decision

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.

Adult age comparisons in the processing of event frequency information.

The usual superiority in frequency-of-occurrence judgments of younger vs. older subjects was hypothesized to result from greater strategic encoding of the materials conveying frequency information. A subject-paced, visual search task was designed to control nontarget word encoding. Relative frequency judgments for the nontarget word pairs were equally accurate for younger and older subjects, and performance of both groups was above chance. Results suggest that strategic cover-task encoding can induce age differences in incidental frequency processing. Consistent with a nonoptimal as opposed to an optimal view, automatic processes require only minimal capacity for above-chance performance, but additional strategic resources can increase performance. When such additional resources are used more by younger than by older subjects, the former are better in frequency performance.

An Empirical Examination of Visual Analysis Procedures for Clinical Practice Evaluation.

ABSTRACT 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 Nugents (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 Ns and levels of auto-correlation was .66. As they are currently designed, Nugents visual analysis procedures make too many type I errors to be useful.

Misguided multiplication: Creating false memories with numbers rather than words

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 × 7 = ??, 3 × 9 = ??) of a missing multiplication answer lure (e.g., 24). The other half contained problems unrelated to the lure (e.g., 5 × 5 = ??, 11 × 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.

A beautiful day in the neighborhood: What factors determine the generation effect for simple multiplication problems?

In four experiments, we examined the generation effect for the free recall of simple multiplication answers. Large-product-size problems showed a consistent generation-effect advantage over smallproduct-size problems, except when each answer was generated twice, via two different sets of operands (Experiment 2). Also, measures of problem-solution time and strategy use accounted for the largeproduct-size advantage. Across experiments, however, small-product-size problems (but not largeproduct-size problems) showed considerable variation in the size of their generation effect. We discovered that solving small-product-size problems via direct memory retrieval increased the episodic recall probability of other problems that were near neighbors to the generated answer, and we attribute this result to a spreading activation mechanism in semantic memory. A measure of neighbor activations, combined with RT to solve each problem, accounted for 51% of the observed generation-effect variance.

Training Content Variability and the Effectiveness of Learning: An Adult Age Assessment

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 1s 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.