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Description
Frequency effects favoring high print-frequency words have been observed in frequency judgment memory tasks. Healthy young adults performed frequency judgment tasks; one group performed a single task while another group did the same task while alternating their attention to a secondary task (mathematical equations). Performance was assessed by correct and error responses, reaction times, and accuracy. Accuracy and reaction times were analyzed in terms of memory load (task condition), number of repetitions, effect of high vs. low print-frequency, and correlations with working memory span. Multinomial tree analyses were also completed to investigate source vs. item memory and revealed a mirror effect in episodic memory experiments (source memory), but a frequency advantage in span tasks (item memory). Interestingly enough, we did not observe an advantage for high working memory span individuals in frequency judgments, even when participants split their attention during the dual task (similar to a complex span task). However, we concluded that both the amount of attentional resources allocated and prior experience with an item affect how it is stored in memory.
ContributorsPeterson, Megan Paige (Author) / Azuma, Tamiko (Thesis advisor) / Gray, Shelley (Committee member) / Liss, Julie (Committee member) / Arizona State University (Publisher)
Created2013
Description
When people look for things in their environment they use a target template - a mental representation of the object they are attempting to locate - to guide their attention around a scene and to assess incoming visual input to determine if they have found that for which they are searching. However, unlike laboratory experiments, searchers in the real-world rarely have perfect knowledge regarding the appearance of their target. In five experiments (with nearly 1,000 participants), we examined how the precision of the observer's template affects their ability to conduct visual search. Specifically, we simulated template imprecision in two ways: First, by contaminating our searchers' templates with inaccurate features, and second, by introducing extraneous features to the template that were unhelpful. In those experiments we recorded the eye movements of our searchers in order to make inferences regarding the extent to which attentional guidance and decision-making are hindered by template imprecision. We also examined a third way in which templates may become imprecise; namely, that they may deteriorate over time. Overall, our findings support a dual-function theory of the target template, and highlight the importance of examining template precision in future research.
ContributorsHout, Michael C (Author) / Goldinger, Stephen D (Thesis advisor) / Azuma, Tamiko (Committee member) / Homa, Donald (Committee member) / Reichle, Erik (Committee member) / Arizona State University (Publisher)
Created2013
Description
Previous research has shown that people can implicitly learn repeated visual contexts and use this information when locating relevant items. For example, when people are presented with repeated spatial configurations of distractor items or distractor identities in visual search, they become faster to find target stimuli in these repeated contexts over time (Chun and Jiang, 1998; 1999). Given that people learn these repeated distractor configurations and identities, might they also implicitly encode semantic information about distractors, if this information is predictive of the target location? We investigated this question with a series of visual search experiments using real-world stimuli within a contextual cueing paradigm (Chun and Jiang, 1998). Specifically, we tested whether participants could learn, through experience, that the target images they are searching for are always located near specific categories of distractors, such as food items or animals. We also varied the spatial consistency of target locations, in order to rule out implicit learning of repeated target locations. Results suggest that participants implicitly learned the target-predictive categories of distractors and used this information during search, although these results failed to reach significance. This lack of significance may have been due the relative simplicity of the search task, however, and several new experiments are proposed to further investigate whether repeated category information can benefit search.
ContributorsWalenchok, Stephen C (Author) / Goldinger, Stephen D (Thesis advisor) / Azuma, Tamiko (Committee member) / Homa, Donald (Committee member) / Hout, Michael C (Committee member) / Arizona State University (Publisher)
Created2014
Description
Otoacoustic emissions (OAEs) are soft sounds generated by the inner ear and can be recorded within the ear canal. Since OAEs can reflect the functional status of the inner ear, OAE measurements have been widely used for hearing loss screening in the clinic. However, there are limitations in current clinical OAE measurements, such as the restricted frequency range, low efficiency and inaccurate calibration. In this dissertation project, a new method of OAE measurement which used a swept tone to evoke the stimulus frequency OAEs (SFOAEs) was developed to overcome the limitations of current methods. In addition, an in-situ calibration was applied to equalize the spectral level of the swept-tone stimulus at the tympanic membrane (TM). With this method, SFOAEs could be recorded with high resolution over a wide frequency range within one or two minutes. Two experiments were conducted to verify the accuracy of the in-situ calibration and to test the performance of the swept-tone SFOAEs. In experiment I, the calibration of the TM sound pressure was verified in both acoustic cavities and real ears by using a second probe microphone. In addition, the benefits of the in-situ calibration were investigated by measuring OAEs under different calibration conditions. Results showed that the TM pressure could be predicted correctly, and the in-situ calibration provided the most reliable results in OAE measurements. In experiment II, a three-interval paradigm with a tracking-filter technique was used to record the swept-tone SFOAEs in 20 normal-hearing subjects. The test-retest reliability of the swept-tone SFOAEs was examined using a repeated-measure design under various stimulus levels and durations. The accuracy of the swept-tone method was evaluated by comparisons with a standard method using discrete pure tones. Results showed that SFOAEs could be reliably and accurately measured with the swept-tone method. Comparing with the pure-tone approach, the swept-tone method showed significantly improved efficiency. The swept-tone SFOAEs with in-situ calibration may be an alternative of current clinical OAE measurements for more detailed evaluation of inner ear function and accurate diagnosis.
ContributorsChen, Shixiong (Author) / Bian, Lin (Thesis advisor) / Yost, William (Committee member) / Azuma, Tamiko (Committee member) / Dorman, Michael (Committee member) / Arizona State University (Publisher)
Created2012
Description
Military veterans have a significantly higher incidence of mild traumatic brain injury (mTBI), depression, and Post-traumatic stress disorder (PTSD) compared to civilians. Military veterans also represent a rapidly growing subgroup of college students, due in part to the robust and financially incentivizing educational benefits under the Post-9/11 GI Bill. The overlapping cognitively impacting symptoms of service-related conditions combined with the underreporting of mTBI and psychiatric-related conditions, make accurate assessment of cognitive performance in military veterans challenging. Recent research findings provide conflicting information on cognitive performance patterns in military veterans. The purpose of this study was to determine whether service-related conditions and self-assessments predict performance on complex working memory and executive function tasks for military veteran college students. Sixty-one military veteran college students attending classes at Arizona State University campuses completed clinical neuropsychological tasks and experimental working memory and executive function tasks. The results revealed that a history of mTBI significantly predicted poorer performance in the areas of verbal working memory and decision-making. Depression significantly predicted poorer performance in executive function related to serial updating. In contrast, the commonly used clinical neuropsychological tasks were not sensitive service-related conditions including mTBI, PTSD, and depression. The differing performance patterns observed between the clinical tasks and the more complex experimental tasks support that researchers and clinicians should use tests that sufficiently tax verbal working memory and executive function when evaluating the subtle, higher-order cognitive deficits associated with mTBI and depression.
ContributorsGallagher, Karen Louise (Author) / Azuma, Tamiko (Thesis advisor) / Liss, Julie (Committee member) / Lavoie, Michael (Committee member) / Arizona State University (Publisher)
Created2017
Description
In this study, the Bark transform and Lobanov method were used to normalize vowel formants in speech produced by persons with dysarthria. The computer classification accuracy of these normalized data were then compared to the results of human perceptual classification accuracy of the actual vowels. These results were then analyzed to determine if these techniques correlated with the human data.
ContributorsJones, Hanna Vanessa (Author) / Liss, Julie (Thesis director) / Dorman, Michael (Committee member) / Borrie, Stephanie (Committee member) / Barrett, The Honors College (Contributor) / Department of Speech and Hearing Science (Contributor) / Department of English (Contributor) / Speech and Hearing Science (Contributor)
Created2013-05
Description
The purpose of this study was to identify acoustic markers that correlate with accurate and inaccurate /r/ production in children ages 5-8 using signal processing. In addition, the researcher aimed to identify predictive acoustic markers that relate to changes in /r/ accuracy. A total of 35 children (23 accurate, 12 inaccurate, 8 longitudinal) were recorded. Computerized stimuli were presented on a PC laptop computer and the children were asked to do five tasks to elicit spontaneous and imitated /r/ production in all positions. Files were edited and analyzed using a filter bank approach centered at 40 frequencies based on the Mel-scale. T-tests were used to compare spectral energy of tokens between accurate and inaccurate groups and additional t-tests were used to compare duration of accurate and inaccurate files. Results included significant differences between the accurate and inaccurate productions of /r/, notable differences in the 24-26 mel bin range, and longer duration of inaccurate /r/ than accurate. Signal processing successfully identified acoustic features of accurate and inaccurate production of /r/ and candidate predictive markers that may be associated with acquisition of /r/.
ContributorsBecvar, Brittany Patricia (Author) / Azuma, Tamiko (Thesis advisor) / Weinhold, Juliet (Committee member) / Berisha, Visar (Committee member) / Arizona State University (Publisher)
Created2017
Description
It has been suggested that directed forgetting (DF) in the item-method paradigm results from selective rehearsal of R items and passive decay of F items. However, recent evidence suggested that the passive decay explanation is insufficient. The current experiments examined two theories of DF that assume an active forgetting process: (1) attentional inhibition and (2) tagging and selective search (TSS). Across three experiments, the central tenets of these theories were evaluated. Experiment 1 included encoding manipulations in an attempt to distinguish between these competing theories, but the results were inconclusive. Experiments 2 and 3 examined the theories separately. The results from Experiment 2 supported a representation suppression account of attentional inhibition, while the evidence from Experiment 3 suggested that TSS was not a viable mechanism for DF. Overall, the results provide additional evidence that forgetting is due to an active process, and suggest this process may act to suppress the representations of F items.
ContributorsHansen, Whitney Anne (Author) / Goldinger, Stephen D. (Thesis advisor) / Azuma, Tamiko (Committee member) / Brewer, Gene (Committee member) / Homa, Donald (Committee member) / Arizona State University (Publisher)
Created2011
Description
The bilingual experience is an often-studied multivariate phenomenon with a heterogeneous population that is often described using subtypes of bilingualism. “Bilingualism” as well as its subtypes lack consistent definitions and often share overlapping features, requiring researchers to measure a number of aspects of the bilingual experience. Different variables have been operationalized to quantify the language proficiencies, use, and histories of bilinguals, but the combination of these variables and their contributions to these subtypes often vary between studies on bilingualism. Research supports that these variables have an influence not only on bilingual classification, but also on non-linguistic outcomes including perceptions of self-worth and bicultural identification. To date, there is a lack of research comparing the quantification of these bilingual subtypes and these non-linguistic outcomes, despite research supporting the need to address both. Person-centered approaches such as latent profile analysis (LPA) and fuzzy set qualitative comparative analysis (fsQCA) have been applied to describe other multivariate constructs with heterogeneous populations, but these applications have yet to be used with bilingualism. The present study integrates models of bilingualism with these analytic methods in order to quantitatively identify latent profiles of bilinguals, describe the sets of conditions that define these subtypes, and to characterize the subjective experiences that differentiate these subtypes. The first study uses an existing data set of participants who completed the Language and Social Background Questionnaire (LSBQ) and performs LPA and fsQCA, identifying latent profiles and the sets of conditions that these subtypes. The following studies use a second set of bilinguals who also completed the LSBQ as well as a supplementary questionnaire, characterizing their identification with biculturalism and their feelings of self-worth. The analyses are repeated with these data to describe the profiles within these data and the subjective experiences in common. Finally, all analyses are repeated with the combined datasets to develop a final model of bilingual subtypes, describing the differences in language use and history within each subtype. Results demonstrate that latent models can be used to consistently characterize bilingual subtypes, while also providing additional information about the relationship between individual bilingual history and attitudes towards cultural identification.
ContributorsMcGee, Samuel (Author) / Azuma, Tamiko (Thesis advisor) / Gray, Shelley (Committee member) / Roscoe, Rod (Committee member) / Grimm, Kevin (Committee member) / Arizona State University (Publisher)
Created2022