Demystifying omega squared: Practical guidance for effect size in common analysis of variance designs.

Omega squared (ω^2) is a measure of effect size for analysis of variance (ANOVA) designs. It is less biased than eta squared, but reported less often. This is in part due to lack of clear guidance on how to calculate it. In this paper, we discuss the logic behind effect size measures, the problem with eta squared, the history of omega squared, and why it has been underused. We then provide a user-friendly guide to omega squared and partial omega squared for ANOVA designs with fixed factors, including one-way, two-way, and three-way designs, using within-subjects factors and/or between-subjects factors. We show how to calculate omega squared using output from SPSS. We provide information on the calculation of confidence intervals. We examine the problems of nonadditivity, and intrinsic versus extrinsic factors. We argue that statistical package developers could play an important role in making the calculation of omega squared easier. Finally, we recommend that researchers report the formulas used in calculating effect sizes, include confidence intervals if possible, and include ANOVA tables in the online supplemental materials of their work. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Strategic use of internal and external memory in everyday life: episodic, semantic, procedural, and prospective purposes.

Humans have access to both internal memory (information stored in the brain) and external memory (information stored in the environment). To what extent do we use each in everyday life? In two experiments, participants rated both internal and external memory for frequency of use, dependability, ease of use (Experiment 1), and likelihood of use (Experiment 2) across four purposes: episodic, semantic, procedural, and prospective. Experiment 1 showed that internal memory was favoured for episodic and procedural purposes, while external memory was favoured for semantic purposes. Experiment 2 further clarified that internal memory was favoured for episodic and common procedural purposes, while external memory was favoured for uncommon semantic, uncommon procedural, and far-term prospective purposes. This strategic division of labour plays to the strengths of both forms of memory. Participants also generally rated external memory as more dependable and easier to use. Results support the memory symbiosis framework.

What characteristics make self-generated memory cues effective over time?

From writing to-do lists to creating mnemonic devices in school, people frequently generate cues to help them remember information. Creating memory cues is a vital aspect of metacognition and allows learners to somewhat control their retrieval circumstances. Across three experiments, we tested the extent to which self-generated memory cues fail at long retention intervals because they are based in fleeting mental states. Participants studied target words and generated mnemonic cues for themselves or for others. Cues intended for others showed greater cue-to-target associative strength, were less distinctive, and were less idiosyncratic (more common) than cues intended for oneself. However, the effectiveness of the cues in supporting recall did not differ by intended recipient at medium (∼3 days) or long (∼1 year) retention intervals. In the third experiment, we directly tested the stability of self-generated cues for oneself (compared to cues for others, descriptions of the target, and focused descriptions) by asking participants to generate cues twice for the same targets across a delay of 3 weeks. Cues intended for others were more stable than all other cues, but the stability of the cues did not affect long term retention. Implications for effective cue generation are discussed.

Identifying the guilty word: Simultaneous versus sequential lineups for DRM word lists.

Recent research in the eyewitness identification literature has investigated whether simultaneous or sequential lineups yield better discriminability. In standard eyewitness identification experiments, subjects view a mock-crime video and then are tested only once, requiring large samples for adequate power. However, there is no reason why theories of simultaneous versus sequential lineup performance cannot be tested using more traditional recognition memory tasks. In two experiments, subjects studied DRM (Deese-Roediger-McDermott) word lists (e.g., bed, rest, tired, ...) and were tested using "lineups" in which six words were presented either simultaneously or sequentially. A studied word (e.g., tired) served as the guilty suspect in target-present lineups, unstudied related words (e.g., nap) served as fillers in target-present and target-absent lineups, and critical lures (e.g., sleep) were included in some target-present and target-absent lineups as well, to serve as attractive alternatives to the target word (or suspect). ROC analyses showed that the simultaneous test format generally yielded superior discriminability performance compared to the sequential test format, whether or not the critical lure was present in the lineup.

Benefits from retrieval practice are greater for students with lower working memory capacity.

We examined the effects of retrieval practice for students who varied in working memory capacity as a function of the lag between study of material and its initial test, whether or not feedback was given after the test, and the retention interval of the final test. We sought to determine whether a blend of these conditions exists that maximises benefits from retrieval practice for lower and higher working memory capacity students. College students learned general knowledge facts and then restudied the facts or were tested on them (with or without feedback) at lags of 0-9 intervening items. Final cued recall performance was better for tested items than for restudied items after both 10 minutes and 2 days, particularly for longer study-test lags. Furthermore, on the 2-day delayed test the benefits from retrieval practice with feedback were significantly greater for students with lower working memory capacity than for students with higher working memory capacity (r = -.42). Retrieval practice may be an especially effective learning strategy for lower ability students.

Simultaneous Versus Sequential Presentation in Testing Recognition Memory for Faces.

Three experiments examined the issue of whether faces could be better recognized in a simul- taneous test format (2-alternative forced choice [2AFC]) or a sequential test format (yes-no). All experiments showed that when target faces were present in the test, the simultaneous procedure led to superior performance (area under the ROC curve), whether lures were high or low in similarity to the targets. However, when a target-absent condition was used in which no lures resembled the targets but the lures were similar to each other, the simultaneous procedure yielded higher false alarm rates (Experiments 2 and 3) and worse overall performance (Experi- ment 3). This pattern persisted even when we excluded responses that participants opted to withhold rather than volunteer. We conclude that for the basic recognition procedures used in these experiments, simultaneous presentation of alternatives (2AFC) generally leads to better discriminability than does sequential presentation (yes-no) when a target is among the alterna- tives. However, our results also show that the opposite can occur when there is no target among the alternatives. An important future step is to see whether these patterns extend to more realistic eyewitness lineup procedures. The pictures used in the experiment are available online at http://www.press.uillinois.edu/journals/ajp/media/testing_recognition/.

Metacognition of multitasking: How well do we predict the costs of divided attention?

Risky multitasking, such as texting while driving, may occur because people misestimate the costs of divided attention. In two experiments, participants performed a computerized visual-manual tracking task in which they attempted to keep a mouse cursor within a small target that moved erratically around a circular track. They then separately performed an auditory n-back task. After practicing both tasks separately, participants received feedback on their single-task tracking performance and predicted their dual-task tracking performance before finally performing the 2 tasks simultaneously. Most participants correctly predicted reductions in tracking performance under dual-task conditions, with a majority overestimating the costs of dual-tasking. However, the between-subjects correlation between predicted and actual performance decrements was near 0. This combination of results suggests that people do anticipate costs of multitasking, but have little metacognitive insight on the extent to which they are personally vulnerable to the risks of divided attention, relative to other people.

Metacognition of the testing effect: guiding learners to predict the benefits of retrieval.

If the mnemonic benefits of testing are to be widely realized in real-world learning circumstances, people must appreciate the value of testing and choose to utilize testing during self-guided learning. Yet metacognitive judgments do not appear to reflect the enhancement provided by testing Karpicke & Roediger (Science 319:966-968, 2008). In this article, we show that under judicious conditions, learners can indeed reveal an understanding of the beneficial effects of testing, as well as the interaction of that effect with delay (experiment 1). In that experiment, subjects made judgments of learning (JOLs) for previously studied or previously tested items in either a cue-only or a cue-target context, and either immediately or after a 1-day delay. When subjects made judgments in a cue-only context, their JOLs accurately reflected the effects of testing, both immediately and at a delay. To evaluate the potential of exposure to such conditions for promoting generalized appreciation of testing effects, three further experiments elicited global predictions about restudied and tested items across two study/test cycles (experiments 2, 3, and 4). The results indicated that learners' global naïve metacognitive beliefs increasingly reflect the beneficial effects of testing when learners experience these benefits with increasing external support. If queried under facilitative circumstances, learners appreciate the mnemonic enhancement that testing provides on both an item-by-item and global basis but generalize that knowledge to future learning only with considerable guidance.

Adaptive and qualitative changes in encoding strategy with experience: evidence from the test-expectancy paradigm.

Three experiments demonstrated learners' abilities to adaptively and qualitatively accommodate their encoding strategies to the demands of an upcoming test. Stimuli were word pairs. In Experiment 1, test expectancy was induced for either cued recall (of targets given cues) or free recall (of targets only) across 4 study-test cycles of the same test format, followed by a final critical cycle featuring either the expected or the unexpected test format. For final tests of both cued and free recall, participants who had expected that test format outperformed those who had not. This disordinal interaction, supported by recognition and self-report data, demonstrated not mere differences in effort based on anticipated test difficulty, but rather qualitative and appropriate differences in encoding strategies based on expected task demands. Participants also came to appropriately modulate metacognitive monitoring (Experiment 2) and study-time allocation (Experiment 3) across study-test cycles. Item and associative recognition performance, as well as self-report data, revealed shifts in encoding strategies across trials; these results were used to characterize and evaluate the different strategies that participants employed for cued versus free recall and to assess the optimality of participants' metacognitive control of encoding strategies. Taken together, these data illustrate a sophisticated form of metacognitive control, in which learners qualitatively shift encoding strategies to match the demands of anticipated tests.

Benefits of Accumulating Versus Diminishing Cues in Recall.

Optimizing learning over multiple retrieval opportunities requires a joint consideration of both the probability and the mnemonic value of a successful retrieval. Previous research has addressed this trade-off by manipulating the schedule of practice trials, suggesting that a pattern of increasingly long lags-"expanding retrieval practice"-may keep retrievals successful while gradually increasing their mnemonic value (Landauer & Bjork, 1978). Here we explore the trade-off issue further using an analogous manipulation of cue informativeness. After being given an initial presentation of English-Iñupiaq word pairs, participants received practice trials across which letters of the target word were either accumulated (AC), diminished (DC), or always fully present. Diminishing cues yielded the highest performance on a final test of cued recall. Additional analyses suggest that AC practice promotes potent (effortful) retrieval at the cost of success, and DC practice promotes successful retrieval at the cost of potency. Experiment 2 revealed that the negative effects of AC practice can be partly ameliorated by providing feedback after each practice trial.

The effects of end-of-day picture review and a sensor-based picture capture procedure on autobiographical memory using SenseCam.

Emerging "life-logging" technologies have tremendous potential to augment human autobiographical memory by recording and processing vast amounts of information from an individual's experiences. In this experiment undergraduate participants wore a SenseCam, a small, sensor-equipped digital camera, as they went about their normal daily activities for five consecutive days. Pictures were captured either at fixed intervals or as triggered by SenseCam's sensors. On two of five nights, participants watched an end-of-day review of a random subset of pictures captured that day. Participants were tested with a variety of memory measures at intervals of 1, 3, and 8 weeks. The most fruitful of six measures were recognition rating (on a 1-7 scale) and picture-cued recall length. On these tests, end-of-day review enhanced performance relative to no review, while pictures triggered by SenseCam's sensors showed little difference in performance compared to those taken at fixed time intervals. We discuss the promise of SenseCam as a tool for research and for improving autobiographical memory.