Two experiments were conducted to investigate how performance on a primary rock climbing task is affected by the inclusion of a secondary word memory task. In Experiment 1, twelve experienced rock climbers completed a dual traverse climb and word memory task, with participants’ performance analysed relative to their single task performance (climbing alone and word memory alone). Participants’ climbing efficiency and word recall were significantly lower in the dual-task condition. Experiment 2 examined the effects of emotional content on climbing performance. Fifteen experienced rock climbers completed two dual-tasks, in which they were asked to recall negatively valenced or neutral words. Climbing efficiency, climbing distance, and word recall were all significantly lower in the dual-task conditions, relative to the single-task conditions. Climbing efficiency and climbing distance were also significantly lower in the negative word dual-task, relative to the neutral word dual-task. The findings from these two experiments have important human factors implications for occupational settings that require climbing-like operations, including search and rescue and fire-fighting.

Purpose: To investigate the effects of speaker age, speaker gender, semantic context, signal-to-noise ratio (SNR) and a listener’s hearing status on speech recognition and listening effort in older adults. We examined the hypothesis that older adults would recognize less speech and exert greater listening effort when listening to the speech of younger versus older adult speakers. Method: Speech stimuli were recorded from 12 adult speakers classified as “younger” (three males and three females aged 18-31 years) and “older” (three males and three females aged 69-89) respectively. A computer-based subjective rating was conducted to confirm that the speakers were representative of younger and older speakers. Listeners included 20 older adults (aged 65 years and above), who were divided into two age-matched groups with and without hearing loss. All listening and speaking participants in the study were native speakers of New Zealand English. A dual-task paradigm was used to measure speech recognition and listening effort; the primary task involved recognition of target words in sentences containing either high or low contextual cues, while the secondary task required listeners to memorise the target words for later recall, following a set number of sentences. Listening tasks were performed with a variety of listening conditions (quiet, +5 dB SNR and 0dB SNR). Results: There were no overall differences in speech recognition scores or word recall scores for the 20 older listeners, when listening to the speech of the younger versus older speakers. However, differential effects of speaker group were observed in the two semantic context conditions (high versus low context). Older male speakers were the easiest to understand when semantic context was low; however, for sentences with high semantic context, the older male group were the most difficult to understand. Word recall scores were also significantly higher in the most challenging listening condition (low semantic context, 0 dB SNR), when the speaker was an older male. Conclusion: Differential effects of speaker group were observed in the two semantic context conditions (high versus low context) suggesting that different speech cues were used by listeners, as the level of context varied. The findings provide further evidence that, in challenging listening conditions, older listeners are able to use a wide range of cues, such as prosodic features and semantic context to compensate for a degraded signal. The availability of these cues depends on characteristics of the speaker, such as rate of speech and prosody, as well as characteristics of the listener and the listening environment. .

Abstract This research investigated the extent to which taking notes influenced the quality of mock jurors’ decisions. High quality decisions were defined in this research as those which did not reflect the influence of the offender stereotype. The impact of note taking on the quality of jurors’ decisions is central to the judicial community’s concerns about note taking as a jury aid and their willingness to offer it in trial contexts. Previous research has argued that note takers make better quality decisions than non-note takers because note takers recall more trial content and make judgements that better reflect the evidence presented. However, according to dual process models of persuasion, high quality decisions should show evidence of both effortful processing of information and no influence of peripheral cues, such as stereotypes. To date, the existing literature has neglected to consider the extent to which note takers, as compared to non-note takers, are influenced by peripheral cues. The current research sought to address this by investigating the extent to which note taking and non-note taking mock jurors were influenced by stereotypes when making decisions in a mock criminal trial. In particular, note taking and non-note taking mock jurors were presented with a criminal trial in which either a male or female defendant had been charged with a stereotypically masculine crime (e.g., aggravated robbery or murder). The extent to which mock jurors were more likely to convict the male defendant and acquit the female defendant was used as a marker of the extent that stereotypes about offenders influenced participants in these studies. Across studies, note takers’ perceptions of guilt, evaluation of the defendant, and, in some instances, recall of trial content, reflected stereotype-based processing while the corresponding measures for non-note takers did not. This research then went on to investigate why note takers were more vulnerable to the influence of stereotypes than non-note takers. It was proposed that one reason might be the requirement that note takers simultaneously record and evaluate trial content. Previous research has shown that persons engaged in dual tasks rely on stereotypes to increase information processing efficiency and are therefore able to re-direct cognitive resources to the additional task. Consistent with previous studies, the current research found that both note takers and mock jurors engaged in an additional task during the trial were more vulnerable to the influence of stereotypes than non-note takers. Furthermore, whilst investigating interventions designed to reduce the influence of stereotypes on note takers’ decisions, results revealed that such interventions were less successful in improving decision quality than interventions that removed the requirement to engage in dual tasks. In particular, the influence of stereotypes was reduced when note takers were encouraged to elaborate on the content of their notes during designated review periods. Whilst methodological features of this research program--namely a reliance on student samples and the relative brevity of mock trials used--may have led to an underestimation of the reliance on stereotypes for note takers, the research has implications for the instructions given to jurors about note taking in judicial contexts. Specifically, the central conclusion of the thesis is that it would seem prudent to amend instructions to direct note takers to engage in the effortful review of their notes prior to coming together to reach a verdict.

Abstract This research investigated the extent to which taking notes influenced the quality of mock jurors’ decisions. High quality decisions were defined in this research as those which did not reflect the influence of the offender stereotype. The impact of note taking on the quality of jurors’ decisions is central to the judicial community’s concerns about note taking as a jury aid and their willingness to offer it in trial contexts. Previous research has argued that note takers make better quality decisions than non-note takers because note takers recall more trial content and make judgements that better reflect the evidence presented. However, according to dual process models of persuasion, high quality decisions should show evidence of both effortful processing of information and no influence of peripheral cues, such as stereotypes. To date, the existing literature has neglected to consider the extent to which note takers, as compared to non-note takers, are influenced by peripheral cues. The current research sought to address this by investigating the extent to which note taking and non-note taking mock jurors were influenced by stereotypes when making decisions in a mock criminal trial. In particular, note taking and non-note taking mock jurors were presented with a criminal trial in which either a male or female defendant had been charged with a stereotypically masculine crime (e.g., aggravated robbery or murder). The extent to which mock jurors were more likely to convict the male defendant and acquit the female defendant was used as a marker of the extent that stereotypes about offenders influenced participants in these studies. Across studies, note takers’ perceptions of guilt, evaluation of the defendant, and, in some instances, recall of trial content, reflected stereotype-based processing while the corresponding measures for non-note takers did not. This research then went on to investigate why note takers were more vulnerable to the influence of stereotypes than non-note takers. It was proposed that one reason might be the requirement that note takers simultaneously record and evaluate trial content. Previous research has shown that persons engaged in dual tasks rely on stereotypes to increase information processing efficiency and are therefore able to re-direct cognitive resources to the additional task. Consistent with previous studies, the current research found that both note takers and mock jurors engaged in an additional task during the trial were more vulnerable to the influence of stereotypes than non-note takers. Furthermore, whilst investigating interventions designed to reduce the influence of stereotypes on note takers’ decisions, results revealed that such interventions were less successful in improving decision quality than interventions that removed the requirement to engage in dual tasks. In particular, the influence of stereotypes was reduced when note takers were encouraged to elaborate on the content of their notes during designated review periods. Whilst methodological features of this research program--namely a reliance on student samples and the relative brevity of mock trials used--may have led to an underestimation of the reliance on stereotypes for note takers, the research has implications for the instructions given to jurors about note taking in judicial contexts. Specifically, the central conclusion of the thesis is that it would seem prudent to amend instructions to direct note takers to engage in the effortful review of their notes prior to coming together to reach a verdict.

The effects that cellular (cell) phone conversation may have on pedestrian road-crossing performance is unknown. A series of experiments was conducted using a virtual reality road crossing simulator to examine this issue. The participants were primarily university students aged between 18 and 24 years old, although one study compared a group aged 18 to 24 to a group between 50 and 67 years old. Two experimental situations were used: a gap-choice situation, in which the participants had to choose a gap to cross through; and an infrequency situation, where vehicles were present on only 10% of the trials. Participants were impaired by a simulated phone conversation task when compared to no-conversation task, as evidenced by longer reaction times, slower walking speeds, poorer gap choices, and more cautious behaviours. Most importantly, conversation was related to a decrease in the mean margins of safety, and the participants were hit or nearly hit by vehicles more often when talking. The general performance of the older participants did not differ from that of the younger participants, and both groups were impaired to a similar extent by the conversation task. Participants were found to use irrelevant distance information to inform their gap-choice decisions, a strategy associated with a decrease in safety as the distance between the vehicles increased. It was also found that their use of time-to-arrival information was impaired when engaged in the conversation task. Overall, talking on a cell phone while crossing a road may represent an unnecessary increase in risk; therefore, care should be taken if these two acts are being conducted concurrently.

A Sociedade Internacional de Continência (ICS) define que toda queixa de perda involuntária de urina é considerada incontinência urinária (IU), sendo que a IU é um processo natural do envelhecimento que afeta de 25 a 45% das mulheres brasileiras. Portadores de IU podem apresentar alterações no controle postural, pois a musculatura do assoalho pélvico é responsável pela estabilização das estruturas da pelve, possuindo assim íntima relação com o controle postural estático. Em virtude disto, o presente estudo tem por objetivo comparar o controle postural de mulheres idosas com relato de perdas urinárias e idosas continentes, nas condições de olhos abertos, supressão da visão e durante teste de dupla tarefa cognitiva e visual. Trata-se de um estudo do tipo observacional de caráter transversal, quantitativo realizado com 46 mulheres idosas, sendo 26 com incontinência urinária com média de idade 68,31 ± 5,79 anos e 20 continentes com média de idade 69,3 ± 6,87 anos. Foi utilizado um questionário de anamnese, para identificar aspectos gerais de saúde das idosas, onde incluía auto relato de perda urinária. A análise do controle postural foi realizada utilizando-se uma plataforma de força para a obtenção dos dados referentes ao centro de pressão (COP). As idosas foram avaliadas nas situações: olhos abertos, olhos fechados e teste de dupla tarefa stroop color. Os dados foram analisados utilizando-se o programa estatístico SPSS 17.0. A normalidade foi verificada através do teste de Shapiro-Wilk e após, realizado teste t de Student e o nível de significância adotado foi de 5%. Os resultados não apresentaram diferenças estatisticamente significativas em todas as variáveis do COP na situação de olhos abertos, nem nas variáveis COPap e COPml de olhos fechados bem como no COPap, COPml e COPvel na dupla tarefa. E as variáveis COPvel e COPelp na situação de olhos fechados e COPelp na dupla tarefa, apresentaram diferenças estatisticamente significativas com p<0,05. Concluiu-se que as mulheres idosas com relato de perdas urinárias apresentaram um pior desempenho do controle postural estático no que se refere a velocidade média de oscilação e a área de oscilação, quando comparadas as idosas continentes. / The International Continence Society (ICS) defines that every complaint involuntary loss of urine are considered urinary incontinence (UI). The UI is a natural process of aging and affects 25-45% of Brazilian women. IU carriers may show changes in postural control, because the pelvic floor muscles is responsible for stabilization of pelvic structures, thus having intimate relationship with the static postural control. This study analyzed and compared the postural control of elderly women with urinary incontinence and continent. The data collection conditions were with eyes open, suppression of vision and with dual cognitive and visual task. It is an observational study of transversal, quantitative conducted with 46 elderly women, 26 UI with a mean age 68.31 ± 5.79 years and 20 continent with a mean age 69.3 ± 6.87 years. The anamnesis questionnaire was used to identify general aspects of health of older, which included urinary loss self-reported. The analysis of postural control was performed using a force plate to obtain data on the center of pressure (COP). The elderly were evaluated in situations: eyes open, eyes closed and dual task Stroop color test. Data were analyzed using SPSS17.0 statistical software, data normality was verified using the Shapiro-Wilk test and after, performed t Student test, and Statistical significance was set at a p-value< 0.05. The results no significant differences for all variables to COP in open eyes, COPap and COPml in closed eyes situations, and COPap, COPml e COPvel in dual task. The results were statistically significant with p<0,05 for variables COPvel and COPelp in closed eyes situations and COPelp in dual task. It was concluded that older women reporting urinary losses showed a worse performance of the static postural control COPvel and COPelp in relation to continent women.

The strength model of self-control predicts that when people exert self-control, they should show performance decrements on subsequent self-control tasks. However, it is possible that this pattern of behaviour is confined to specific experimental procedures, which amplifies the effect. The aims of this thesis are to; 1) test the strength model predictions in sport; and 2) examine emotion as a mediator of self-control performance effects. Study 1 consisted of two experiments. Experiment 1 set out to demonstrate a pattern of resource depletion. Forty-three sport and exercise students performed either an incongruent (self-control depletion) or congruent (control) Stroop task before and after performing a virtual reality cycling task on an indoor cycling ergometer. Findings showed the depletion group performed worse on the second Stroop task than on their first task or than the control group. Experiment 2 sought to address some of the methodological concerns in Experiment 1, and examine emotion as a factor explaining performance. Forty-eight physically active participants followed the same experimental protocol, but with an additional iteration of both tasks. Results demonstrated that both cycling and Stroop task performance improved across time. In addition, participants reported feeling happier and more motivated during the second cycling task. Study 2 provided a conceptual replication of Study 1, using different tests of self-control. Twenty-six university-level male soccer players either performed the Loughborough Soccer Passing Test (LSPT) with (self-control depletion) or without (control) an audio file simulating crowd noise, and then performed the wall squat muscle endurance test. The self-control depletion group reported feeling more anxious during the LSPT and performed worse than the controls on the wall squat. III Next, in Study 3, nineteen well-trained competitive endurance runners performed a self-paced 1600 m running trial and then ran a second trial either self-paced or with a pacemaker. The pacemaker had no significant effect on actual performance time but participants reported feeling more anxious beforehand and adopted a fast start strategy, whereas the self-paced group had a conservative pacing pattern. Study 4 showed that, for females, consuming a sports drink—as opposed to plain water—associated with better physical (high-intensity track running) and cognitive self-control (Stroop) performance. In addition, they appeared to be happier drinking water, and more anxious drinking the sports drink—an effect that diverged over the six weeks. Study 5 examined the effects of three strategies—designed to increase or decrease the intensity of emotions—on emotion, pacing strategy and 1600 m performance. Results showed the intervention designed to decrease unpleasant emotions was associated with lower anxiety, higher calmness, a slower first 400 m, and more overall consistent pacing strategy. Study 6 examined the effects of imagery training on swimming tumble-turn performance. Findings showed no significant intervention effect, a result that goes against the proposed benefits of psychological skills training and runs counter to the predictions of the strength model. Collectively, the evidence in the thesis provides limited support for the strength model. It is concluded that self-control performance does not inevitably deteriorate across self-control tasks where the individual is well-versed with the task demands, or where tasks are not physically strenuous enough to tax mental resources. In contrast, the explanation for performance deterioration across a series of novel tasks is likely to extend beyond that of a self-control resources perspective. Future research might profitably test this proposal.

Background: When people walk while performing a cognitive dual-task, a decrease in gait velocity will occur because of the demand for some of the same cognitive resources. However, in a previous study they found an increase instead of a decrease in gait velocity when subjects walked on a self-paced treadmill while performing a color-word Stroop task. Aim: The aim of this study was to determine if the increase found in gait velocity in the previous study was a consequence of the subjects’ position. Additionally, it was investigated whether real-time feedback about the subjects’ position could substitute the lack of a reference point. Method: Position and gait velocity was measured in twelve healthy subjects during a trial consisting of eight control conditions and eight different interventions. Results: A significant difference was found in gait velocity between the interventions where the accelerations-line was moved furthest to the front and back (IzerolineA, IzerolineB) and in position between the original intervention and one with a neutral zone (Iorginal1, Ineutralzone). No differences were found in position or velocity with any of the feedback systems. Conclusion: From the results it could be concluded that the increase in gait velocity was a consequence of the subjects positioning themselves further in the forward direction on the treadmill. No conclusions could be drawn with the feedback systems.

xiv, 96 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Among older adults, an impaired ability to maintain balance while simultaneously performing cognitive tasks is a common occurrence. Because poor dual-task balance performance is associated with increased fall risk and a decline in cognitive function, interventions to improve dual-task balance performance are needed. Although traditional rehabilitation programs emphasizing training balance under single-task conditions are effective in improving single-task balance performance, it is not known whether single-task training generalizes to balance control under dual-task contexts. Moreover, the effectiveness of approaches to training balance under dual-task conditions is not known. Thus, the purposes of this study were to determine whether elderly individuals with balance impairment can improve their balance performance under dual-task conditions; to investigate whether training balance under single-task conditions generalizes to balance control during dual-task contexts; and to evaluate the effect of instructional set on dual-task balance performance. Specifically, the efficiency of three different training strategies was examined in an effort to understand the mechanisms underlying training-related changes in dual-task balance performance. Twenty-three elderly adults with balance impairment were randomly assigned to 1 of 3 interventions: single-task balance training (ST); dual-task training with fixed-priority instruction (FP); and dual-task training with variable-priority instruction (VP). Clinical and laboratory measures were obtained at baseline and after training. In addition, selected clinical outcomes were repeated after the second week of training to examine interim balance change and at twelve weeks post training to test retention. Results indicate that dual-task training was effective in improving balance under dual-task conditions in the elderly with balance impairment. Training balance under single-task conditions may not generalize to balance control during dual-task contexts. Explicit instruction regarding attentional focus was an important factor for improvement in dual-task performance. The VP instructional set offered advantages over the FP instructional set in terms of the degree of improvement, the rate of learning, and the retention of the dual-task training effect. The dual-task processing skills learned during training were not transferred to novel dual-task conditions. Lastly, the training benefits acquired during VP training could be the result of both automatization of the individual task and the development of task-coordination skills. / Adviser: Marjorie Woollacott

xiii, 103 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / The purpose of this dissertation was (1) to investigate the effects of dual task conditions on the development of postural control during gait in typically developing children while walking and obstacle crossing, and (2) to investigate the attentional requirements of gait in children with cerebral palsy (CP). Forty younger and older typically developing (YTD and OTD) children and 10 children with CP performed a gait task with and without a concurrently auditory Stroop task. Gait and cognitive performance were measured. In study 1, dual task interference with gait performance was found in YTD and OTD children, but not in healthy young adults (HYA). In general, gait performance decrements under dual task contexts were greater in YTD than OTD children, whereas cognitive performance decrements during dual tasking were not different between the two groups of children. Dual task interference was lowest in HYA and highest in YTD children when compared among groups. As the difficulty of the gait task was increased, dual task affects on cognitive performance were now found in YTD and OTD children, but not HYA. In study 2, there were significant differences in dual task interference affecting gait performance in all groups of children. When performing the gait task with a concurrent auditory Stroop task, OTD children showed greater dual-task costs than children with CP for accuracy, but children with CP demonstrated greater dual-task costs than OTD and YTD children for medial Center of Mass-Ankle-joint-center inclination angle. This increased medio-lateral inclination angle in dual task situations has also been seen in older adults with balance deficits and may be associated with an increased risk for falls. YTD children showed dual-task costs in a slowing of gait velocity and stride time, a safer strategy than that used by children with CP. The lower cognitive performance during dual tasking for OTD children suggests that they allocate greater attention to maintain gait stability, whereas YTD children and children with CP do not. In addition, children with CP use a behavior that may increase their risk of falls in complex environments. This dissertation includes unpublished co-authored material. / Committee in charge: Marjorie Woollacott, Chairperson, Human Physiology; Paul van Donkelaar, Member, Human Physiology; Li-Shan Chou, Member, Human Physiology; Paul Dassonville, Outside Member, Psychology