Doctoral Dissertations and Master’s Theses   

Doctoral Dissertation
Author: Shana K. Carpenter (2004)
Title: A Multiple-Cue Hypothesis for the Testing Effect
Advisor: Ed DeLosh
Abstract: Three experiments investigated the role of variable processing in the testing effect. All three experiments utilized a paired-associate paradigm in which the same target items were presented, followed by an intervening cued-recall test or additional study opportunity, followed by a final free-recall test over all target items. In Experiment 1, related cue-target pairs (dough: bread) were presented, followed by either an intervening test in which the cue was either the same or different from the one encountered during initial presentation (dough: ______, toast: ______, respectively), or by an intervening study opportunity in which the cue was either the same or different from the one encountered during initial presentation (dough: bread, toast: bread, respectively). In Experiment 2, cue-target pairs were the same from initial presentation to intervening test or study, and were either highly related (dough: bread) or weakly related (basket: bread). In Experiment 3, unrelated cue-target pairs (basket: bread) were presented, followed by either a yes/no recognition test or additional study opportunity in which the correct target was presented after either 0 incorrect targets (basket: bread), 1 incorrect target (basket: wicker, basket: bread), 2 incorrect targets (basket: wicker, basket: eggs, basket: bread), or 3 incorrect targets (basket: wicker, basket: eggs, basket: carry: basket: bread). A significant testing effect was obtained in all three experiments. In addition, a significant advantage in retention was obtained for target items presented with different as opposed to same cues (Experiment 1), a significant Trial x Cue Interaction was obtained in which retention for tested items benefited from unrelated as opposed to related cues whereas retention for studied items was unaffected by cue-target relatedness (Experiment 2), and finally, retention for studied items but not tested items benefited significantly from a greater number of incorrect targets such that the relative advantage for tested over studied items decreased with each additional incorrect target (Experiment 3). Results of these three experiments suggest that retention for both tested and studied items can benefit from variable processing, and that the advantage for tested over studied items is greatest under conditions that promote the sampling of extra information during retrieval.

Masters Thesis
Author: Shana K. Carpenter (2003)
Title: Interpreting the Effects of Memory Enhancement Through Testing: Cue Effectiveness Versus Item Difficulty
Advisor: Ed DeLosh
Abstract: Manipulations designed to decrease an item’s accessibility in at the time of an intervening test often increase retention for that item later on. The current study set out to untangle the effects of two manipulations—cue effectiveness and item difficulty—that have been confounded in past research. Seventy-two participants were presented with word lists, followed by either an additional study opportunity or a cued-recall test that provided the first letter of each word. If retrieval was unsuccessful, participants were provided with additional letters until the item was successfully retrieved, so all items were assumed to be cued effectively while difficulty varied according to the number of letters required. On a test of retention, test trials were superior to study trials, but difficulty had a negative impact. Explanations are considered based on early failed retrieval attempts, and the differential effects of the difficulty of items versus the difficulty of retrieval conditions.

Masters Thesis
Author: Gwen Schmidt (2003)
Title: Metaphor Processing as an Indicator of Course Semantic Processing in the Right Hemisphere
Advisor: Carol Seger
Abstract: The purpose of this study was to explore the possibility that processing metaphors involves the right hemisphere (RH) in right-handed normal populations. In addition, theories that explain why metaphors may involve the RH are explored. One theory suggests that metaphor processing in the RH is part of a more general function of the RH, coarse semantic coding (Beeman, 1998). The left hemisphere (LH) mediates semantic relationships between words having high semantic feature overlap, whereas the RH activates a broader semantic network of more distantly related words. Bottini et al. (1994) present an alternate view, proposing that the interpretation of a metaphor requires access to one's experience (stored in episodic memory). A divided visual field procedure was used to determine which of these approaches is supported. Literal and metaphorical sentences from Bottini et al. were presented in the left (lvf-RH) and right (rvf-LH) visual fields of normal individuals. The literal sentences involved unusual uses of objects, containing distant semantic relationships. The results showed a RH advantage for both the literal and metaphorical sentences, providing further evidence for the notion that the RH is involved in certain aspects of language comprehension including metaphor processing (from the metaphorical sentences) and also more generally the processing of semantically distant words (from both literal and metaphorical sentences). Metaphor processing thus appears to be subsumed under the more general concept of coarse semantic coding. Consequently the results provide support for the coarse semantic coding model of semantic processing in the RH proposed by Beeman. Because both literal and metaphorical sentences showed a RH advantage, a difference between the processing of these two types of sentences as suggested by Bottini et al. is not supported.

Doctoral Dissertation
Author: Paul S. Merritt (2002)
Title: Modality Specific Contributions to True and False Recognition: An Event-Related Potential Study
Advisor: Ed DeLosh
Abstract: Retrieval in recognition memory is generally thought to operate based on two distinct processes, recollection and familiarity. The contribution of modality specific information to these processes is unclear, however. The Deese/Roediger and McDermott (D/RM) paradigm was used to create a situation in which test items differed according to perceptual experience, with old items associated with a previous sensory experience, but lure items not associated with such an experience. Additionally the modality of study lists was manipulated such that participants either saw or heard items at study, then were tested visually, such that there was a match or mismatch in study-test modality. Event-related potentials (ERPs) were used to provide a precise measurement of recognition memory processes as they unfolded. Significant differences were found for several ERP components. The P300 was larger for participants in the visual study condition and for false alarms to lure items. Analysis of the FN400 component revealed higher amplitudes for false alarms compared to hits in the visual study condition, but lower amplitudes for false alarms than hits in the auditory condition. A parietal old/new effect was found in the auditory but not the visual condition, with hits and false alarms producing ERPs consistent with recollection and familiarity processes, respectively. Finally, late frontal effects were found which indicated that participants in the visual condition were engaging in greater post-retrieval evaluation than those in the auditory condition. This effect was driven by a large late frontal positivity for false alarms in the visual study condition. These results are interpreted as indicating a possible retrieval strategy difference between the study modality conditions, consistent with an explanation based on distinctiveness.

Masters Thesis
Author: Julie M. Bugg (2001)
Title: Effects of Physical Activity and Time of Day on Older Adults' Executive Control Performance
Advisor: Ed DeLosh
Abstract: Existing research reveals two interesting patterns regarding age-related changes in executive control functioning. First, some studies show that physical exercise can alleviate or counteract the age-related decline in executive control functioning. Second, the performance of older adults on executive control tasks is often better in the morning than evening, whereas the reverse is true among younger adults. The present study further examines the effect of physical activity on older adults' executive control functioning and also explores whether physical activity mediates the observed decline in cognitive functioning across the day. Thirty-nine older adults (mean age = 73.58) completed inhibition, working memory, and sustained attention tasks during a morning session and an evening session. Participants were grouped into active and sedentary groups based on their scores on a self-report measure of physical activity, with the active group comprised of the 13 participants with the highest physical activity scores and the sedentary group comprised of the 13 participants with the lowest physical activity scores. Active participants performed reliably better than the sedentary participants on the sustained attention task, whereas performance did not differ between groups on the inhibition or working memory tasks.   Additionally, whereas performance on the sustained attention and inhibition tasks was similar across the day for both groups, working memory performance was better in the morning than the evening for sedentary participants, while this effect did not hold for active participants. This supports the idea that time-of-day effects may reflect lower cognitive "endurance" among older adults, endurance that may be maintained through physical activity.

Masters Thesis
Author: Corinna Cincotta (2001)
Title: Differences in Event Related Potentials as a Function of Category Learning Mode
Advisor: Carol Seger
Abstract: An ERP (Event Related Potential) category-learning study compared brain activity between good learners and poor learners, and differences between rule and memory based strategies.  Participants categorized imaginary animals into two different categories. The categories were structured so that each animal could be successfully categorized on the basis of a rule or memory. Good learners (n = 40) were defined as performing at or above 75% correct (poor learners, n = 31). Good learners were classified as rule (n = 7) or memory learners (n = 30) based on their responses to ambiguous test trials (rule or memory strategies predict opposite category membership) and a questionnaire. The grand average ERPs showed differences between good learners and poor learners: good learners had higher amplitude ERPs from 200 ms to 700 ms. Rule learners had higher amplitudes in posterior electrodes from 200-700 ms than memory learners. In anterior electrodes, exemplar learners showed higher amplitudes at earlier latencies (200-350ms) and rule learners showed higher amplitudes at later latencies (350-700 ms). The results suggest that rule learning is associated with higher visual area activity and memory learning shows earlier activation of frontal lobe areas than rule learning. Although rule and memory learning have been presented at times as mutually exclusive, these results indicate that both strategies may be used and may be associated with different patterns of brain activity.

Masters Thesis
Author: Paul S. Merritt (1999)
Title: A Self-Terminating Search Account of Memory-Based Decisions
Advisor: Ed DeLosh
Abstract: Research regarding memory-based decision making has to this point been inconsistent in both methodology and results. A new account describing memory-based decision making as involving a self-terminating memory search is proposed, along with a paradigm for investigating the model. Replicating and extending on work conducted by Anderson and Hubert (1963), three experiments were conducted in which participants were given lists of adjectives and asked to make likableness ratings about a person described by those adjectives, as well as a job-suitability rating in Experiment 3. Participants engaged in both memory-based judgments and on-line judgments, with the judgment-recall order manipulated. In general, items recalled correlated with judgments for memory-based decisions, but not on-line decisions. The self-terminating search account of memory-based decisions was in general supported by the results. The results are discussed in terms of the account, the importance of encoding objectives is discussed and suggestions for further study are made.