The contributions of strategy use to working memory span: A comparison of strategy assessment methods

In two experiments, we tested whether individual differences in strategy production account for individual differences in performance on a working memory span task. We measured the strategies used during a standard experimenter-paced operation span (OSPAN) task by having participants make both set-by-set reports of strategy use for individual item sets and global reports of strategy use. In Experiment 1, although normatively effective strategies were self-reported on only a small proportion of OSPAN sets, individual differences in effective strategy use correlated with span performance. Experiment 2 replicated this outcome using a sample of 100 participants but, as important, it demonstrated that individual differences in effective strategy use did not mediate the relationship between OSPAN and measures of verbal ability. Discussion focuses on the interpretation of strategy–span relationships and the relative utility of general reports of strategy use versus the set-by-set reports introduced here for the OSPAN task.     

Strategy use in the reading span test: An analysis of eye movements and reported encoding strategies

Strategy use in the traditional reading span test was examined by recording participants’ eye movements during the task (Experiment 1) and by interviewing participants about their strategy use (Experiment 2). In Experiment 1, no differences between individuals with a low, medium, and high span were observed in how they distributed processing time between task elements. In all three groups, fixation times on words up to the to-be-remembered (TBR) word became shorter and the time spent on the TBR longer as memory load in the task increased. The results of Experiment 2, however, show that span groups differ in the use of memory encoding strategies: individuals with a low span use mainly rehearsal, whereas individuals with a high span use almost exclusively semantic elaboration. The results indicate that the use of elaborative strategies may enhance span performance but that not all individuals are necessarily able to use such strategies efficiently.     

Negations in syllogistic reasoning: Evidence for a heuristic–analytic conflict

Research indicates that cognitive age differences can be influenced by metacognitive factors. This research has generally focused on simple memory tasks. Age differences in working memory (WM) performance are pronounced, but are typically attributed to basic cognitive deficits rather than metacognitive factors. However, WM performance can be influenced by strategic behaviour that might be driven by metacognitive monitoring. In the current project, we attempted to connect these lines of research by examining age differences in metacognitive WM monitoring and strategies. In Experiment 1, younger and older adult participants completed a computerized operation span task in conditions that either required or did not require monitoring reports. Participants in the monitoring condition predicted and postdicted global performance for each block and rated their responses following each trial within a block. In Experiment 2, participants also reported their trial-level strategic approach. In contrast to the age equivalence typically found for simple memory monitoring, results demonstrated age differences in WM monitoring accuracy. Overall age differences in strategy use were not found, but using effective strategies benefited older adults' performance more than younger adults'. Furthermore, age-related differences in the WM task appear to be mediated by the accuracy of performance monitoring.     

Strategy use in the reading span test: an analysis of eye movements and reported encoding strategies

Strategy use in the traditional reading span test was examined by recording participants' eye movements during the task (Experiment 1) and by interviewing participants about their strategy use (Experiment 2). In Experiment 1, no differences between individuals with a low, medium, and high span were observed in how they distributed processing time between task elements. In all three groups, fixation times on words up to the to-be-remembered (TBR) word became shorter and the time spent on the TBR longer as memory load in the task increased. The results of Experiment 2, however, show that span groups differ in the use of memory encoding strategies: individuals with a low span use mainly rehearsal, whereas individuals with a high span use almost exclusively semantic elaboration. The results indicate that the use of elaborative strategies may enhance span performance but that not all individuals are necessarily able to use such strategies efficiently.     

Supertaskers: Profiles in extraordinary multitasking ability

Theory suggests that driving should be impaired for any motorist who is concurrently talking on a cell phone. But is everybody impaired by this dual-task combination? We tested 200 participants in a high-fidelity driving simulator in both single- and dual-task conditions. The dual task involved driving while performing a demanding auditory version of the operation span (OSPAN) task. Whereas the vast majority of participants showed significant performance decrements in dual-task conditions (compared with single-task conditions for either driving or OSPAN tasks), 2.5% of the sample showed absolutely no performance decrements with respect to performing single and dual tasks. In single-task conditions, these “supertaskers” scored in the top quartile on all dependent measures associated with driving and OSPAN tasks, and Monte Carlo simulations indicated that the frequency of supertaskers was significantly greater than chance. These individual differences help to sharpen our theoretical understanding of attention and cognitive control in naturalistic settings.     

Working memory capacity and strategy use

In this study, we examine the role of strategy use in working memory (WM) tasks by providing short-term memory (STM) task strategy training to participants. In Experiment 1, the participants received four sessions of training to use a story-formation (i.e., chaining) strategy. There were substantial improvements from pretest to posttest (after training) in terms of both STM and WM task performance. Experiment 2 demonstrated that WM task improvement did not occur for control participants, who were given the same amount of practice but were not provided with strategy instructions. An assessment of participants' strategy use on the STM task before training indicated that more strategic participants displayed better WM task performance and better verbal skills. These results support our hypothesis that strategy use influences performance on WM tasks.     

The irrelevant sound phenomenon revisited: what role for working memory capacity?

High-span individuals (as measured by the operation span [OSPAN] technique) are less likely than low-span individuals to notice their own names in an unattended auditory stream (A. R. A. Conway, N. Cowan, & M. F. Bunting, 2001). The possibility that OSPAN accounts for individual differences in auditory distraction on an immediate recall test was examined. There was no evidence that high-OSPAN participants were more resistant to the disruption caused by irrelevant speech in serial or in free recall. Low-OSPAN participants did, however, make more semantically related intrusion errors from the irrelevant sound stream in a free recall test (Experiment 4). Results suggest that OSPAN mediates semantic components of auditory distraction dissociable from other aspects of the irrelevant sound effect.     

Contribution of strategy use to performance on complex and simple span tasks

Simple and complex span tasks are widely thought to measure related but separable memory constructs. Recently, however, research has demonstrated that simple and complex span tasks may tap, in part, the same construct because both similarly predict performance on measures of fluid intelligence (Gf) when the number of items retrieved from secondary memory (SM) is equated (Unsworth & Engle, Journal of Memory and Language 54:68–80 2006). Two studies (n = 105 and n = 152) evaluated whether retrieval from SM is influenced by individual differences in the use of encoding strategies during span tasks. Results demonstrated that, after equating the number of items retrieved from SM, simple and complex span performance similarly predicted Gf performance, but rates of effective strategy use did not mediate the span-Gf relationships. Moreover, at the level of individual differences, effective strategy use was more highly related to complex span performance than to simple span performance. Thus, even though individual differences in effective strategy use influenced span performance on trials that required retrieval from SM, strategic behavior at encoding cannot account for the similarities between simple and complex span tasks.     

From poor performance to success under stress: working memory, strategy selection, and mathematical problem solving under pressure

Two experiments demonstrate how individual differences in working memory (WM) impact the strategies used to solve complex math problems and how consequential testing situations alter strategy use. In Experiment 1, individuals performed multistep math problems under low- or high-pressure conditions and reported their problem-solving strategies. Under low-pressure conditions, the higher individuals' WM, the more likely they were to use computationally demanding algorithms (vs. simpler shortcuts) to solve the problems, and the more accurate their math performance. Under high-pressure conditions, higher WM individuals used simpler (and less efficacious) problem-solving strategies, and their performance accuracy suffered. Experiment 2 turned the tables by using a math task for which a simpler strategy was optimal (produced accurate performance in few problem steps). Now, under low-pressure conditions, the lower individuals' WM, the better their performance (the more likely they relied on a simple, but accurate, problem strategy). And, under pressure, higher WM individuals performed optimally by using the simpler strategies lower WM individuals employed. WM availability influences how individuals approach math problems, with the nature of the task performed and the performance environment dictating skill success or failure.     

Interference resolution in the elderly: evidence suggestive of differences in strategy on measures of prepotent inhibition and dual task processing

The ability to effectively resolve interference was investigated in young and elderly participants using a test of inhibition and a dual task measure. The tasks stressed the ability to suppress prepotent responding, and balance primary and secondary task demands, respectively. Successful performance on both measures hinged on the ability to minimize the distraction generated between competing aspects of each task. Increasing demands resulted in performance decrements despite titration for individual differences in span size and generalized slowing. These were more pronounced on the hardest condition of each task, especially in older participants. Furthermore, the nature of the decrements suggested the use of different strategies between groups. It is argued that a fundamental source of the age-associated variability in cognition is due to compromised ability to effectively resolve interference, and cannot be sufficiently explained by memory span differences or generalized slowing.     

Sources of individual differences in working memory: Contributions of strategy to capacity

Some research on attentional control in working memory has emphasized theoretical capacity differences. However, strategic behavior, which has been relatively unexplored, can also influence attentional control and its relationship to cognitive performance. In two experiments, we examined the relationship between attentional control (measured with operation span) and interference in a part-list cuing paradigm. Paradoxically, the results indicated that superior attentional control was related to increased interference. This relationship reflected the participants’ use of more complex encoding strategies, rather than superior interference control at retrieval, and was eliminated following brief encoding strategy training. The results suggest that complex span measures sometimes predict individual differences in task strategies related to interference control and that these strategies may be amenable to training. The implications for working memory research and the roles of strategies in basic memory and attention paradigms are briefly discussed.     

Why does working memory span predict complex cognition? Testing the strategy affordance hypothesis

We introduce and empirically evaluate the strategy affordance hypothesis, which holds that individual differences in strategy use will mediate the relationship between performances on a working memory (WM) span task and another cognitive task only when the same strategies are afforded by both tasks. One hundred forty-eight participants completed basic memory tasks and verbal span tasks that afford the same strategies, such as imagery and sentence generation, and completed reading comprehension tasks that afford different ones, such as self-questioning and summarization. Effective strategy use on WM span tasks accounted for variance in the span-memory relationship, but not for the span-comprehension relationship, supporting the strategy affordance hypothesis. Strategy use mediated the span-cognition relationship only when both tasks afforded the same strategies.     

External validation of the computerized, group administrable adaptation of the “operation span task”

One of the most widely used tasks for measuring working memory capacity is the operation span task (OSPAN; Turner & Engle, 1989). This task has almost always been applied individually, and stimuli presentation is controlled by the experimenter. Recently, De Neys, d'Ydewalle, Schaeken, and Vos (2002) improved the administration procedure by designing an automated, group-administrable version of the task (GOSPAN). They found GOSPAN to be reliable, and they also provided evidence on its validity (a significant positive correlation between GOSPAN and OSPAN scores). However, an external test of GOSPAN validity is still lacking. In this work, we present such a validation for the automated version, when the task is administered both individually (Experiment 1) and to groups (Experiment 2). There are abundant previous data on the relation between working memory capacity and reading comprehension. In this work, this relation is studied using an automated OSPAN version to measure working memory capacity. Given that our results are similar to those found using the original OSPAN, our data support the external validity of the automated version of the task. We also tested the reliability of the task and found high internal consistency in both experiments.     

An individual differences analysis of ability and strategy influences: age-related differences in associative learning

The relationships among abilities, strategies, and performance on an associative learning task were investigated for young (aged 17 to 34) and older adults (aged 60 to 82). Participants received extensive practice on a noun-pair task in which they could use a visual-scanning strategy or a memory-retrieval strategy. Older adults were more likely to use the scanning strategy. Age differences were reduced when comparisons were made only for participants using a retrieval strategy. Associative memory was predictive of learning on the task, and semantic memory access speed was predictive of practiced performance. Practiced performance on a memory-search task that also required associative learning was predictive of practiced noun-pair performance. Models of ability-performance relationships for skill acquisition are discussed.     

Reasoning strategies: the role of working memory and verbal-spatial ability

Evidence increasingly suggests individual differences in strategies adopted on reasoning tasks and that these are either verbal-propositional or visuospatial in nature. However, the cognitive foundations of these strategies remain uncertain. Experiment 1 examined the relationship between the use of working memory resources and strategy selection for syllogistic reasoning. Verbal and spatial strategy users did not differ on working memory capacity, but confirmatory factor analysis indicated that while verbal reasoners draw primarily on verbal working memory, spatial reasoners use both this and spatial resources. Experiment 2 investigated the relationship between strategies and verbal and spatial abilities. Although strategy groups were similar in overall ability, regression analysis showed that performance on a spatial ability measure (Vandenberg mental rotation task) predicted syllogistic reasoning performance, but only for spatial strategy users. The findings provide converging evidence that verbal and spatial strategies are underpinned by related differences in fundamental cognitive factors, drawing differentially on the subcomponents of working memory and on spatial ability.     

Adult age differences in subjective and objective measures of strategy use on a sequentially cued prediction task

Differences in strategy use are thought to underlie age-related performance deficits on many learning and decision-making tasks. Recently, age-related differences in learning to make predictions were reported on the Triplets Prediction Task (TPT). Notably, deficits appeared early in training and continued with experience. To assess if age differences were due to early strategy use, neural networks were used to objectively assess the strategies implemented by participants during Session 1. Then, the relationship between these strategies and performance was examined. Results revealed that older adults were more likely to implement a disadvantageous strategy early in learning, and this led to poorer task performance. Importantly, the relationship between age and task performance was partially mediated by early strategy use, suggesting that early strategy selection played a role in the lower quality of predictions in older adults.     

Older and younger adults' strategies in approximate quantification

In two experiments, participants were asked to provide a quick and rough estimate of the number of items in collections of 4-79 items. In Experiment 1 verbal strategy reports and performance on each item were collected, and in Experiment 2 performance and eye movements were collected, while young and older participants were tested in strategy-instructed conditions. Results showed that: (a) participants used six different estimation strategies, (b) overall, young and older participants used the same set of strategies, but varied in how often they used each strategy, (c) older adults' strategy repertoire was smaller than young adults' (i.e., inter-individual differences in strategy repertoire), (d) strategy use, participants' performance, and eye movements varied as a function of numerosities and configurations of items, (e) in both the age groups, each strategy was associated with distinctive performance measures and eye movement patterns. These findings show that different processes are available for approximate quantification in both young and older adults and that aging is associated with strategic variations.     

Attentional control and the relatedness proportion effect in semantic priming

In 2 experiments, participants completed both an attentional control battery (OSPAN, antisaccade, and Stroop tasks) and a modified semantic priming task. The priming task measured relatedness proportion (RP) effects within subjects, with the color of the prime indicating the probability that the to-be-named target would be related. In Experiment 2, participants were cued before each trial with the probability of a related target. Stimulus onset asynchronies traditionally thought to tap automatic processing (267 ms) versus controlled processing (1,240 ms) were used. Across experiments, principal component analysis on the battery revealed a general attentional control component. Moreover, the RP effect increased linearly with attentional control in both experiments. It is concluded that RP effects produced in this paradigm depend purely upon the effortful process of expectancy generation, which renders them sensitive to individual differences in attentional control.     

Distinguishing the contributions of implicit and explicit processes to performance of the weather prediction task

Examinations of the cognitive neuroscience of category learning frequently rely on probabilistic classificationlearning Tasks—namely, the weather prediction task (WPT)—to study the neural mechanisms of implicit learning. Accumulating evidence suggests that the task also depends on explicit-learning processes. The present investigation manipulated the WPT to assess the specific contributions of implicit- and explicit-learning processes to performance, with a particular focus on how the contributions of these processes change as the task progresses. In Experiment 1, a manipulation designed to disrupt implicit-learning processes had no effect on classification accuracy or the distribution of individual response strategies. In Experiment 2, by contrast, a manipulation designed to disrupt explicit-learning processes substantially reduced classification accuracy and reduced the number of participants who relied on a correct response strategy. The present findings suggest that WPT learning is not an effective tool for investigating nondeclarative learning processes     

Content and strategy in syllogistic reasoning.

Syllogistic reasoning has been investigated as a general deductive process (Johnson-Laird & Byrne, 1991; Revlis, 1975; Rips, 1994). However, several studies have demonstrated the role of cognitive strategies in this type of reasoning. These strategies focus on the method used by the participants (Ford, 1995; Gilhooly, Logie, Wetherick, & Wynn, 1993) and strategies related to different interpretations of the quantified premises (Roberts, Newstead, & Griggs, 2001). In this paper, we propose that content (as well as individual cognitive differences) is an important factor in inducing a certain strategy or method for syllogistic resolution. Specifically, we suggest that syllogisms with a causal conditional premise that can be extended by an agency premise induce the use of a conditional method. To demonstrate this, we carried out two experiments. Experiment 1 provided evidence that this type of syllogism leads participants to draw the predicted conditional conclusions, in contrast with control content syllogisms. In Experiment 2, we demonstrated that the drawing of conditional conclusions is based on a causal conditional to an agent representation of the syllogism premises. These results support the role of content as inducing a particular strategy for syllogistic resolution. The implications of these results are discussed.