This study investigated the impacts of dual task and time pressure conditions on the speech fluency of 60 neurotypical adults between the ages of 26 and 85. Participants retold short stories in baseline, time pressure, dual task, and combined dual task and time pressure conditions. Dependent variables included five measures of speech fluency: words per minute (WPM), fillers per verbalization, false starts and repetitions per verbalization, extended pauses per utterance, and speech naturalness. Each of these variables was compared between age groups of younger, older, and elderly adults and across conditions. Results reveal that time pressure causes speech rate to increase across age groups but combining time pressure with a dual task condition mitigates this effect in elderly speakers. Additionally, younger adults are perceived to have more natural speech compared to older and elderly adults. Speakers across age groups perform similarly in all other variables of speech fluency, with notable changes in fluency under the combined dual task and time pressure condition compared to other conditions. These findings suggest that while speakers do not always become less fluent as attentional demands increase, the combination of dual task and time pressure conditions can cause attentional demands to surpass capacity and/or resource allocation thresholds for fluent speakers. Future research should continue investigating the effect of time pressure and other divided attention conditions on typical speakers and those with communication disorders to establish methods for optimizing conditions for effective communication in everyday situations.

Dual task performance and the interaction of tasks has been the subject of much research. When tasks are performed together they affect each other to varying degrees depending upon such factors as the similarity of the tasks, their difficulty, and whether one task is given preference over another. In this study, task preference was investigated under divided attention conditions in order to determine what effect preference had on task performance. Twenty young adults took part in this study and were randomly assigned into two groups. Each group was experimentally motivated to favor one of the two tasks – either speaking a "tongue-twister" or tracking a moving target on a screen with a computer mouse. Each participant performed the tasks in both an isolated and combined conditions. The measurements of task performance (tracking scores, utterance duration, lower lip and jaw displacement, lower lip and jaw velocity, upper lip-lower lip correlation, spatiotemporal index, and sound pressure level) were then analyzed to determine how task preference affected the participant's performance. It was expected that the preferred task's performance would not suffer when performed in the dual task situation. Although some trends were noted in the predicted direction, no statistically significant results were found as a function of task preference. There were, however, some gender effects. Men were found to have significantly higher intensity than women during the speaking tasks in both the dual and isolated task conditions, and they were also found to perform better than women on the motor tracking task in both the dual and isolated task conditions.

This study evaluated the possible influence of linguistic demands on speech motor control by measuring articulatory movement stability during conditions of increasing grammatical complexity. There were 60 participants in three age groups: 20-30 years, 40-50 years, and 60-70 years, with equal numbers of men and women in each group. These speakers produced 10 repetitions of five different sentence or phrase conditions. These five conditions included two baseline measurements and three sentences of varying complexity. Each complexity condition had an MLU count of 23, word length of 17, syllable length of 25, and contained the phrase open boxes of pompoms. Complexity was measured by node-count and grammatical structure. Lower lip movements during production of the target phrase were used to compute the spatiotemporal index (STI), a measure of lip movement stability over 10 repetitions. It was predicted that STI would be lower (indicating greater stability) in the baseline and low complexity conditions. Comparison of complexity conditions against the baseline-counting condition demonstrated significant differences in the upper lip's STI, displacement, and velocity, as well as in vocal intensity. Speech motor differences between the grammatical complexity levels were minimal and could be attributed to several factors, such as speaking rate or semantic differences. An unexpected finding of this study was the influence of age on speech production. Participants from the 60 year-old group had significantly longer utterance duration, while those from the 20 year-old group had the highest lower lip and jaw STI values. These findings suggest that speech motor control matures even beyond young adulthood and that linguistic complexity does not appear to have a consistent effect on speech movement variables.

This study examined the effects of concurrent speech and computer tasks on each other and on measures of physiologic arousal in 30 young adults. Physiologic measures included galvanic skin response, heart rate, and heart rate variability. Participants completed a speech-only task, two computer-based tasks, and combined speech and computer-based tasks. Participants spoke for 60 seconds on a procedural discourse prompt. Acoustic measures included the mean and standard deviation of intensity and fundamental frequency as indices of prosody, speaking time ratio to reflect pausing, and speech rate. The primary computer task (with two levels of difficulty) involved making formatting changes to a paragraph with a word processor. The secondary computer task involved data entry (typing items from a shopping list into categories in a spreadsheet). Errors were tallied for each computer task. Statistical analysis revealed a significant decrease in words per minute in both the data entry and the easier formatting tasks; the proportion of speaking time decreased for all three concurrent computer tasks. Performance on all computer tasks was negatively impacted by speech. There was a significant decrease in the number of words correctly sorted and the number of correct formatting changes. The physiologic changes were limited; it remains unclear whether the heart rate increases during combined computer task and speaking conditions resulted from the addition of cognitive load or the respiratory changes inherent in speaking compared to silent task performance. Findings reflect bidirectional interference between speech and computer-based tasks while multitasking. These findings can help speech-pathologists to create therapy activities that are more like what patients will be experiencing in their everyday lives, such as practicing speech during computer tasks.

This study examined the effects of computer tasks on speech acoustic measures and the effects of speaking on computer task performance in 30 younger and 30 older adults. Participants completed a speech only task, two computer tasks, and simultaneous speaking and computer tasks. Stimulus sentences included the four corner vowels and two diphthongs embedded between voiceless consonants. Acoustic measures of speech included diphthong transition extent and rate as well as vowel space area (VSA) and vowel articulation index (VAI). A text formatting task included two levels of difficulty. A data entry task included sorting items from a shopping list into categories. Statistical analysis revealed that the dual-task conditions led to a significant decrease in diphthong formant transition extent and rate. Speaking while completing the computer tasks led to an increase in diphthong duration. There was also a significant decrease for VSA and VAI for each dual-task condition compared to speaking alone. Diphthong transition extent, diphthong duration, and VAI were higher in the older adult group. Performance on all computer tasks significantly decreased when simultaneously producing speech. Overall, the findings reveal significant bidirectional interference between concurrent speech and computer tasks. The results also suggest older adults have poorer performance in divided attention computer tasks. The older adult participants were found to speak with longer vowel durations and more expansive articulation than the younger adults. The findings from this study may pave the way for future clinical work that may result in assessment and treatment approaches involving divided attention scenarios.

This study examined interference between three non-speech tasks and concurrent speech performance. The non-speech activity consisted of computer-based mathematical, language, and visuospatial tasks. The speech tasks included a procedural discourse monologue and a conversation. Participants included 60 adults in two age groups with 30 participants each. The younger adults were aged from 18 to 30 years and older adults from 55 to 82 years. Each participant completed the non-speech tasks in isolation, the speech tasks in isolation, and then each of the speech tasks concurrently with each of the three non-speech tasks. Speech acoustic measures included the mean and standard deviation of intensity and fundamental frequency as indicators of prosody, speaking time ratio to reflect speaking versus pausing time, and speech rate. Non-speech measures included total responses, correct responses, and accuracy. Statistical analysis revealed significant divided attention effects on speech, with increases in fundamental frequency and decreases in speaking time ratio, speech rate, and intensity. Performance on all non-speech tasks was negatively impacted by speech, as there was a significant decrease in total responses and total correct responses overall. There was a significant age effect for intensity and fundamental frequency variability, in that the younger group had less prosodic variation compared to the older group. The present findings provide some evidence that the effects of divided attention increase with age, as older adults gave fewer responses than younger adults overall. However, results indicate older adults prioritize accuracy over speed compared to younger adults. These findings suggest that bidirectional interference occurs between speech and mathematical, language, and visuospatial tasks. The results expand what is known about bidirectional interference between speech and other concurrent tasks, as well as the effects of age on divided attention.

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This study was divided into two parts. Study 1 examined the spoken language production of neurologically healthy adults (NHA) in selective and divided attention conditions during a story retell task. NHA participant groups consisted of 21 younger (26–54), 19 older (55–69), and 20 elderly (70–85) adults. Study 2 investigated how the language production of four people with aphasia (PWA) compared to their respective NHA group. All participants retold stories in a silent baseline condition, three background noise conditions (cocktail party, conversation, phone call), and one dual-task condition (tone discrimination). Language production measures (speech rate, disfluent verbalizations, language efficiency, lexical diversity, lexical-phonological errors), tone-discrimination accuracy and response time, and perceived effort and stress were compared across groups and conditions. Results of Study 1 revealed that the language of elderly adults was significantly less efficient and had more disfluent verbalizations than that of both younger and older adults, and the language of older adults was significantly less efficient and had more disfluent verbalizations than that of younger adults. The tone discrimination accuracy and response time of elderly adults was significantly lower than that of younger adults. Older and elderly adults showed greater levels of perceived stress than younger adults. Across groups, lexical diversity decreased and lexical-phonological errors and disfluent verbalizations increased during the dual-task and phone call conditions. Costs to tone discrimination accuracy, response time, perceived effort, and perceived stress were found in the dual-task condition across groups. These findings suggest that some, but not all, measures of spoken language production are impacted by aging, and that selective and divided attention interferes with spoken language production for NHA. Results of Study 2 show that the four PWA were distinguished from their respective NHA adult group for all dependent variables in at least one condition. Percent lexical-phonological errors, percent disfluent verbalizations, and speech rate were the dependent variables that distinguished PWA from NHA the most. However, the language production, tone-discrimination response, perceived effort, and perceived stress of each PWA were unique to the individual. These findings suggest that lexical-phonological errors, percent disfluent verbalizations, and speech rate may be useful measures for discerning individuals with mild aphasia from NHA speakers in a variety of conditions.

Yes / Background: Past research has found cancellation tasks to be reliable markers of cognitive decline in Huntington’s disease (HD). Objective: The aim of this study was to extend previous findings by adopting the use of a dual task paradigm that paired cancellation and auditory tasks. Methods: We compared performance in 14 early stage HD participants and 14 healthy controls. HD participants were further divided into groups with and without cognitive impairment. Results: Results suggested that HD participants were not slower or less accurate compared with controls; however, HD participants showed greater dual task interference in terms of speed. In addition, HD participants with cognitive impairment were slower and less accurate than HD participants with no cognitive impairment, and showed greater dual task interference in terms of speed and accuracy. Conclusions: Our findings suggest that dual task measures may be a better measure of cognitive processing in HD compared with more traditional measures. / Supported by the School of Psychological Sciences, Monash University.

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.