INFLUENCES OF SENSORY MODALITY AND STIMULUS TYPE ON PROCESSING TASK-IRRELEVANT STIMULI

Ph.D

Investigation of Inhibitory and Facilitatory Attentional Mechanisms in Cognitive Aging

M.A. University of Hawaii at Manoa 2015.Includes bibliographical references.It is well understood that human cognition declines with age. While much research has explored cognitive decline in the elderly, it is still unknown as to what specific mechanisms underpin this decline. Processing speed theory (Salthouse, 1996) would suggest that any observed differences between elderly and young adult samples are due to a generalized slowing of information processing. On the other hand, inhibitory deficit theory (Hasher & Zacks, 1988) posits that any age related decline in cognition is not related to a general slowdown, but rather to deficits in inhibitory control. The research in this thesis used a dual-task paradigm that has the ability to examine both inhibitory and facilitatory attentional mechanisms in both younger and older adult populations. Overall, the findings from two experiments provide support for both of the theoretical standpoints used to explain cognitive decline. That is, there was evidence for a general slowdown in information processing (Experiments 1 and 2) as well as a disturbance in inhibitory processes (Experiment 1). Thus, it appears that both theories may account for the cognitive decline, at least as measured with these experimental paradigms. The findings also provide evidence for a separate facilitatory attentional mechanism that appears to be less susceptible to age related decline

The role of working memory in melodic perception

We explored the extent to which working memory underpins the processing of relational information in melodies. Using a between subjects design, one group of participants was primed with a melodic stream while performing a concurrent 2-back task while the other group was also primed with the melodic stream but did not perform a concurrent task. Participants were then given a melodic relational categorization task where relations (melodic contour and intervals) could either match or not match the primed melody. Reaction times on the categorization task for primed melodies tended to be faster than for non-primed melodies in the notask condition, suggesting that relational information in melodies could influence behavior more under conditions where working memory resources were not being used in concomitant tasks. Given the marginal results, more data should be collected to ascertain the full extent to which working memory is involved in the processing of relational melodic content

Effect of Aging on Inhibitory Attentional Mechanisms

The ability to inhibit the processing of irrelevant informationdeclines as adults age (Hasher & Zacks, 1988; Lustig, Hasherand Tonev, 2006; Mayr, 2001). However, previous researchinvestigating inhibitory control in older adults has notevaluated the extent to which irrelevant information isprocessed and later recognized. Using a dual task paradigmwith young adults, Dewald, Sinnett, and Doumas (2011)demonstrated inhibited recognition for previously ignoredwords, provided they had appeared infrequently with targetsin the primary task, compared to words that did not appearwith targets. The current study adapted this paradigm toexamine inhibitory mechanisms in a sample of older adults.Here, older adults exhibited inhibited recognition for allwords while young adults continued to show greaterinhibition for words that had appeared with targets comparedto words that had not. This finding suggests that older adultsmay experience a decline in the selective inhibition ofirrelevant information

Differential Processing for Actively Ignored Pictures and Words

Previous work suggests pictures may be processed more readily than words, likely because pictures appear tomaintain more direct access to semantic and conceptual representations (Amit, Algom, & Trope, 2009). However, it is unclearhow words and pictures may be processed differently when they are actively ignored. Our earlier work demonstrated a facilitatedrecognition for actively ignored words, provided they appeared frequently with an attended target in a previously presentedrepetition detection task (Dewald, Sinnett, & Doumas, 2012). The current study adapted this paradigm to examine the extentto which unattended pictures may be processed under analogous conditions. Overall, ignored pictures were recognized moreoften than ignored words. Moreover, recognition for ignored pictures did not benefit from target-alignment whereas ignoredwords did. These findings suggest that unattended pictures may continue to be processed more readily than words even underconditions in which attention is not directed toward them

Differential Processing for Actively Ignored Pictures and Words

This data set contains accuracy and reaction time (RT) scores for participants during a primary identification task and secondary surprise recognition test. For more information regarding the data set, please contact the researcher

Performance accuracy on the surprise recognition test.

<p>Recognition rates and standard error for TA items (dark grey bar) and NA items (light grey bar). “Words” and “Pictures” indicate the stimulus type in the recognition test. Asterisks (*) indicate a significant difference from chance; caret (^) indicates a significant difference between items within a group.</p

Resting-state connectivity and spontaneous activity of ventromedial prefrontal cortex predict depressive symptomology and peripheral inflammation in HIV

Depression and chronic inflammation are common in persons infected with the human immunodeficiency virus (HIV+). Although depression and response to inflammatory challenge are shown to reflect activity in common neural networks, little is known regarding sub-clinical presentation in persons chronically infected with HIV. The relationship of resting-state functional connectivity (rsFC) between the subgenual anterior cingulate cortex (sgACC) and bilateral amygdala to Beck Depression Inventory-1 (BDI) scores were compared within a group of 23 HIV+ and 23 HIV-negative comparison adults. An interaction was found wherein lower rsFC between the sgACC and both right and left amygdala was associated with higher BDI scores in HIV+ individuals. Total BDI scores and plasma levels of IL-6, IL-8, TNF-α, and IL-10 made available from 10 of the HIV+ patients were regressed upon an index of spontaneous whole-brain activity at rest; i.e., the amplitude of low-frequency fluctuations (ALFFs). Elevated levels of depression and IL-6 were associated with increased ALFF in a cluster of voxels on the medial portion of the ventral surface of the frontal lobe (Brodmann Area 11). Within this sample of HIV+ individuals lower rsFC of the sgACC with subcortical limbic regions predicts greater burden of depressive symptomology whereas elevated activity in the adjacent BA 11 may reflect sickness, indexed by elevated IL-6, and associated depressive behaviors