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Thesis (D. Psych.)--Victoria University (Melbourne, Vic.), 2007.

The effective operation of auditory verbal working memory processes is essential to both understanding and communicating in everyday life. These processes are particularly vulnerable to disruption in a wide range of clinical conditions that affect brain functioning. Problems with working memory are frequently the primary reason why people with brain dysfunction are referred for neuropsychological assessment; consequently, verbal memory has been ranked as the second most frequently assessed cognitive ability. However, current psychometric approaches, predominantly serial recall, paired-associate- and list-learning tasks have been designed mainly to detect the presence (and severity) or absence of memory impairment rather than identifying intact or impaired processes. Performance is usually measured by scores of free recall and recognition, with testing procedures that are often lengthy and time-consuming for both patients and clinicians. When assessing working memory, the span tasks have been viewed as “a complete assessment of the function of phonological short-term memory” (Vallar & Papagno, 2002). Digit span, in particular, has come to be regarded as the principal neuropsychological methodology for evaluating the capacity of auditory working memory (Andrewes, 2001), despite doubts about its lack of sensitivity (Lezak, Howieson, & Loring, 2004) and potential to overestimate capacity (Andrewes, 2001). Theoretical advances regarding the underlying component processes of encoding and retrieval have only slowly been incorporated into clinical practice but have not been applied in any systematic or coherent manner. Concepts of working memory have been extended to include semantic, phonological and temporal aspects. One potentially useful approach examined the role of phonological and semantic codes and cues and their susceptibility and immunity to interference effects (Tehan & Humphreys, 1995). Alternatively, another study investigated patients’ ability to accurately retrieve visual information by keeping track of the current episode, differentiating it from previous similar episodes that had the potential to reduce effective performance because of interference effects or poor discrimination (Parkin, Leng, & Hunkin, 1990). The aim of the research reported in this thesis was to develop a more compact cuedretrieval procedure to directly measure the phonological, semantic and temporal aspects of working memory and to examine its clinical usefulness by administering the task to brain injury rehabilitation patients. The conceptual section of the introductory chapter commences with a discussion on memory systems, particularly working memory, and is followed by an examination of some of the core processes involved in successful and unsuccessful remembering (forgetting). The applied section examines traditional and current approaches to memory assessment in clinical practice and their limitations in addressing the clinical needs of patients with memory impairments. Finally, an alternative approach that focuses on specific encoding and cueing processes rather than overall recall, is proposed. Empirical studies are reported in the following four chapters; Chapter 2 described the development and implementation of the initial studies with non-clinical participants, while Chapter 3 described the refinement of the procedure. Semantic and phonological coding and cueing effects were examined within a temporal context. The findings clearly demonstrated that semantic and phonological processes acted in quite distinct and consistent ways, irrespective of the degree of prior exposure to the word stimuli. Participants had more difficulty keeping track of the current episode when the codes and cues were phonological. Following refinements to the stimuli and procedure, replication of the previous results confirmed that cued-retrieval using semantic, phonological and temporal cues was a legitimate approach to memory assessment. Furthermore, differential effects were still found even after significantly shortening the procedure, thus adding support for its potential usefulness in clinical settings. The next two chapters examined the clinical application of this alternative approach in brain injury rehabilitation patients. The ability of non-clinical participants and brain injury rehabilitation patients to effectively use codes and cues to retrieve verbal information was compared. Quite distinct profiles indicated that the cued-retrieval procedure clearly differentiated clinical and non-clinical participants. Brain injury patients obviously performed more poorly on both semantic and phonological tasks but they also demonstrated a reduced ability to effectively use phonological codes and cues in retrieving information, as their performance declined across successive episodes due to increasing interference effects. Finally, the cued-retrieval procedure was administered to brain injury patients in the context of routine, post-injury, comprehensive neuropsychological assessment to examine the comparative value of this process approach in relation to other currently used clinical tests of verbal and working memory. The results clearly indicated that cued-retrieval was more sensitive in detecting memory impairments than most of the other tests in current use and, due to its brevity, was able to provide this information relatively quickly. The closing chapter summarized and integrated the empirical findings of these research studies and highlighted the implications for future clinical practice and further research. The preliminary evidence clearly indicated that this brief and sensitive method of examining the underlying processes of verbal working memory has clinical and theoretical potential.

This study investigated learning and memory performance similarities and differences between healthy, Spanish-speaking older adults of Hispanic/Latino descent and English-speaking Caucasian older adults. It explored the possibility that the novelty of verbal memory tasks, along with cultural and educational differences, may lead to performance differences in Spanish-speaking older adults' effective use of organizational strategies, such as semantic clustering. It hypothesized that an alternative strategy instruction, which provided explicit detail on how to use the effective semantic clustering strategy, would reduce differences observed between the Hispanic and Caucasian groups. Forty-eight healthy, Spanish-speaking older adults and 55 healthy, English-speaking older adults were administered list-learning tasks in their dominant language. Under standard task instruction, Spanish-speaking older adults with low levels of formal education learned fewer words on the task than Caucasian and Hispanic participants who had higher levels of education. Hispanic participants, regardless of educational levels, also utilized semantic clustering recall at lower rates than Caucasian participants under standard instruction. When provided with explicit strategy instruction, both groups showed reduced list learning, and Hispanic older adults demonstrated reduced response to strategy manipulation compared to Caucasian participants. Finally, in the Hispanic older adult sample, the quality of their formal education and level of acculturation were identified as important predictors of verbal learning outcomes. These findings highlight the need to continue to examine the complex role of demographic and cultural variables on verbal learning and memory processes, as they may impact the assessment of pathological processes such as dementia, as well as the development of effective cognitive interventions for diverse elders.

Šiuo tyrimu siekta atsakyti į klausimą, ar priklausomų nuo narkotinių medžiagų asmenų autobiografiniai prisiminimai reabilitacijos metu skiriasi nuo nepriklausomų savo konkretumu, dominuojančiais kontekstais bei subjektyviu vertinimu. Tikslui pasiekti buvo atliekamas pusiau struktūruotas interviu individualiai su 16 Vilniaus priklausomybės ligų centro ilgalaikės reabilitacijos skyriuje esančių nuo priklausomybės narkotikais besigydančių asmenų bei 15 sveikų panašaus amžiaus vyrų. Priklausomų asmenų amžiaus vidurkis buvo 26,56 metai (SD=2,73), o kontrolinės grupės amžiaus vidurkis – 24,06 (SD=1,75). Iš viso buvo surinkti 186 prisiminimai, kurie kiekvienas buvo nepriklausomų vertintojų užkoduotas pagal parengtą kodavimo schemą. Kodavimo schema buvo sudaryta iš keturių kontekstų kategorijų, joje taip pat buvo prašoma įvertinti prisiminimų konkretumą/ neapibrėžtumą, taisyklių laikymąsi. Klinikinės ir kontrolinės grupės buvo lyginamos pagal polinkį atgaminti neapibrėžtus bei konkrečius prisiminimus, polinkį juos vertinti neigiamai arba teigiamai, dominuojančius kontekstus. Abiejų grupių papasakoti ankstyvieji prisiminimai buvo lyginami pagal jų subjektyvų vertinimą bei išsiskiriančius kontekstus. Neapibrėžtumo/ konkretumo savybė buvo lyginama tarp grupių pateiktų prisiminimų į emocinius raktinius žodžius. Iš šių prisiminimų taipogi buvo siekiama išskirti dominuojančius kontekstus, palyginti jų subjektyvų vertinimą bei patikrinti kitas jų ypatybes. Nustatyta, jog priklausomų asmenų... [toliau žr. visą tekstą] / This study was conducted to answer the question weather the specificity, dominating contexts or subjective valency of autobiographical memories of drug addicted men during rehabilitation process differ from the ones of non addicted individuals. For this purpose the half structured interview was made with 16 drug addicted patients in Vilnius Center for Addictive Disorders in long-term rehabilitation department and with 15 non addicted men of the same age. Averagely drug addicted men were 26.56 years old (SD=2.73). The mean age of control group was 24.06 (SD=1,75) years. 186 memories were collected. Independent experts coded these memories using the coding scheme. The coding scheme was made of 4 contexts groups, memories’ specificity/ over-generality assessment, assessment weather they are according to instructions or not. The clinical and the control groups were compared according to the tendencies to remember more specific memories; according to more positive or negative memory assessment tendencies and the tendencies to remember the particular things, themes. The early memories of both groups were compared according to subjective emotional assessment and the contexts dominating. Also the specificity/ over-generality feature of the memories recalled to the key words was compared between the two groups. Also it was important to distinguish dominant contexts, compared to their subjective assessment, and verify the other of their characteristics. It was found that drug addicted... [to full text]

A comprehensive battery of commonly used neuropsychological tests, including the WMS Associate Learning and Visual Reproduction subtests, forming the focus of this study, were administered to a southern African sample (n = 33, age range 18-40). This sample composed of black South African, IsiXhosa speakers with an educational level of Grade 11 and 12, derived through DET and former DET schooling. The gender demographics were as follows; females n = 21 and males n = 12. This sample was purposefully selected based on current cross-cultural research which suggests that individuals matching these above-mentioned demographics are significantly disadvantaged when compared to available neuropsychological norms. This is due to the fact that current norms have been created in contexts with socio-cultural influences; including culture, language and quantity and quality of education distinctly dissimilar to individuals like that composed in the sample. Hence the purpose of this study was fourfold namely; 1) Describe and consider socio-cultural factors and the influence on test performance 2) Provide descriptive and preliminary normative data on this neuropsychologically underrepresented population 3) Compare test performance between age and gender through stratification of the sample and finally to 4) Evaluate the current norms of the two WMS subtests and assess their validity for black South Africans with DET and former DET schooling with comparisons to the results found in the study. Information derived from the statistical analyses indicated that a higher performance in favour of the younger group over the older age range was consistently found for both WMS subtests. With regards to gender, some higher means were evident for the male population in the sample than was produced by the female group. Lastly, due to the fact that most scores derived from the sample were considerably lower when compared to the available norms, it is felt that socio-cultural factors prevalent to this population are a significant cause of lower test performance and thus warrant the development of appropriate normative indicators.