Resource allocation during spoken discourse processing: effects of age and passage difficulty as revealed by self-paced listening

Pragmatic Skills in Late Adulthood

Research investigating pragmatic abilities in healthy aging suggests that both production and comprehension might be compromised; however, it is not clear how pragmatic abilities evolve in late adulthood, as well as when difficulties are more likely to arise. The aim of this study is to investigate the decline of pragmatic skills in aging, and to explore what cognitive and demographic factors support pragmatic competence. We assessed pragmatic production skills, including discourse abilities such as speech, informativeness, information flow, paralinguistic aspects, as well as the ability to produce informative descriptions of pictures, and pragmatic comprehension skills, which encompassed the ability to understand discourse and the main aspects of a narrative text, to infer non-literal meanings and to comprehend verbal humor in a group of elderly individuals and in a sample of younger participants. Moreover, specific cognitive functions (short-term memory, verbal and visuospatial working memory, inhibition Theory of Mind, and Cognitive Reserve) were assessed in both groups. Pragmatic difficulties seem to occur in late adulthood, likely around 70 years, and emerge more prominently when participants are asked to understand verbal humor. Age was the only predictor of general pragmatic performance in a sample of cognitively unimpaired older adults; conversely, when elderly individuals with less intact inhibitory control are considered, a general role of inhibition emerged, in addition to working memory and ToM in specific tasks.

Self-pacing ameliorates recall deficit when listening to vocoded discourse: a cochlear implant simulation

Introduction

In spite of its apparent ease, comprehension of spoken discourse represents a complex linguistic and cognitive operation. The difficulty of such an operation can increase when the speech is degraded, as is the case with cochlear implant users. However, the additional challenges imposed by degraded speech may be mitigated to some extent by the linguistic context and pace of presentation.

Methods

An experiment is reported in which young adults with age-normal hearing recalled discourse passages heard with clear speech or with noise-band vocoding used to simulate the sound of speech produced by a cochlear implant. Passages were varied in inter-word predictability and presented either without interruption or in a self-pacing format that allowed the listener to control the rate at which the information was delivered.

Results

Results showed that discourse heard with clear speech was better recalled than discourse heard with vocoded speech, discourse with a higher average inter-word predictability was better recalled than discourse with a lower average inter-word predictability, and self-paced passages were recalled better than those heard without interruption. Of special interest was the semantic hierarchy effect: the tendency for listeners to show better recall for main ideas than mid-level information or detail from a passage as an index of listeners' ability to understand the meaning of a passage. The data revealed a significant effect of inter-word predictability, in that passages with lower predictability had an attenuated semantic hierarchy effect relative to higher-predictability passages.

Discussion

Results are discussed in terms of broadening cochlear implant outcome measures beyond current clinical measures that focus on single-word and sentence repetition.

The development of foraging organization

In foraging tasks, multiple targets must be found within a single display. The targets can be of one or more types, typically surrounded by numerous distractors. Visual attention has traditionally been studied with single target search tasks, but adding more targets to the search display results in several additional measures of interest, such as how attention is oriented to different features and locations over time. We measured foraging among five age groups: Children in Grades 1, 4, 7, and 10, as well as adults, using both simple feature foraging tasks and more challenging conjunction foraging tasks, with two target types per task. We assessed participants' foraging organization, or systematicity when selecting all the targets within the foraging display, on four measures: Intertarget distance, number of intersections, best-r, and the percentage above optimal path length (PAO). We found that foraging organization increases with age, in both simple feature-based foraging and more complex foraging for targets defined by feature conjunctions, and that feature foraging was more organized than conjunction foraging. Separate analyses for different target types indicated that children's, and to some extent adults', conjunction foraging consisted of two relatively organized foraging paths through the display where one target type is exhaustively selected before the other target type is selected. Lastly, we found that the development of foraging organization is closely related to the development of other foraging measures. Our results suggest that measuring foraging organization is a promising avenue for further research into the development of visual orienting.

The neural language systems that support healthy aging: Integrating function, structure, and behavior

Although healthy aging is generally characterized by declines in both brain structure and function, there is variability in the extent to which these changes result in observable cognitive decline. Specific to language, age-related differences in language production are observed more frequently than in language comprehension, although both are associated with increased right prefrontal cortex activation in older adults. The current paper explores these differences in the language system, integrating them with theories of behavioral and neural cognitive aging. Overall, data indicate that frontal reorganization of the dorsal language stream in older adults benefits task performance during comprehension, but not always during production. We interpret these results in the CRUNCH framework (compensation-related utilization of neural circuits hypothesis), which suggests that differences in task and process difficulty may underlie older adults' ability to successfully adapt. That is, older adults may be able to neurally adapt to less difficult tasks (i.e., comprehension), but fail to do so successfully as difficulty increases (i.e., production). We hypothesize greater age-related differences in aspects of language that rely more heavily on the dorsal language stream (e.g., syntax and production) and that recruit general cognitive resources that rely on frontal regions (e.g., executive function, working memory, inhibition). Moreover, there should be a relative sparing of tasks that rely predominantly on ventral stream regions. These results are both consistent with patterns of age-related structural decline and retention and with varying levels of difficulty across comprehension and production. This neurocognitive framework for understanding age-related differences in the language system centers on the interaction between prefrontal cortex activation, structural integrity, and task difficulty.

Age differences in learning from text: The effects of content preexposure on reading

This study investigated age differences in the way in which attentional resources are allocated to expository text and whether these differences are moderated by content preexposure. The organization of the preexposure materials was manipulated to test the hypothesis that a change in organization across two presentations would evoke more processing effort (i.e., a “mismatch effect”). After preexposure, reading time was measured as younger and older adults read a target text to produce recall, answer comprehension questions, and solve a novel problem. Relative to the young, older readers allocated more time as they encountered new discourse entities and showed a stronger serial position effect, which are patterns of resource allocation that suggest more extensive processing of the discourse situation. Younger adults took advantage of repeated exposure to produce more extensive reproduction of text content, as well as more text-specific solutions to solve a problem. Older adults generated more elaborated inferences and were similar to young adults in terms of the dimensional complexity of problem solutions. Whereas younger readers showed weak evidence for a mismatch effect, older readers did not. These data are consistent with the proposal that older readers favor the situation model over textbase content in allocating resources to text, but this effect was not enhanced by introducing organizational difficulty in reprocessing.

The effect of plausibility on sentence comprehension among older adults and its relation to cognitive functions

BACKGROUND/STUDY CONTEXT: Older adults show age-related decline in complex-sentence comprehension. This has been attributed to a decrease in cognitive abilities that may support language processing, such as working memory (e.g., Caplan, DeDe, Waters, & Michaud, 2011,Psychology and Aging, 26, 439-450). The authors examined whether older adults have difficulty comprehending semantically implausible sentences and whether specific executive functions contribute to their comprehension performance.

METHODS

Forty-two younger adults (aged 18-35) and 42 older adults (aged 55-75) were tested on two experimental tasks: a multiple negative comprehension task and an information processing battery.

RESULTS

Both groups, older and younger adults, showed poorer performance for implausible sentences than for plausible sentences; however, no interaction was found between plausibility and age group. A regression analysis revealed that inhibition efficiency, as measured by a task that required resistance to proactive interference, predicted comprehension of implausible sentences in older adults only. Consistent with the compensation hypothesis, the older adults with better inhibition skills showed better comprehension than those with poor inhibition skills.

CONCLUSION

The findings suggest that semantic implausibility, along with syntactic complexity, increases linguistic and cognitive processing loads on auditory sentence comprehension. Moreover, the contribution of inhibitory control to the processing of semantic plausibility, particularly among older adults, suggests that the relationship between cognitive ability and language comprehension is strongly influenced by age.

The Effects of Aging on Auditory Processing and Cognition

Purpose

To briefly summarize existing data on effects of aging on auditory processing and cognition.

Method

A narrative review summarized previously reported data on age-related changes in auditory processing and in cognitive processes with a focus on spoken language comprehension and memory. In addition, recent data on effects of lifestyle engagement on cognitive processes are reviewed.

Results

There is substantial evidence for age-related declines in both auditory processes and cognitive abilities. Accumulating evidence supports the idea that the perceptual burden associated with hearing loss impacts the processing resources available for good comprehension and memory for spoken language, particularly in older adults with limited resources. However, many language abilities are well preserved in old age, and there is considerable variability among individuals in cognitive performance across the life span. The authors discuss how lifestyle factors and socioemotional engagement can help to offset declining abilities.

Conclusions

It is clear that spoken language processing in adulthood and old age is affected by changes in perceptual, cognitive, and socioemotional processes as well as by interactions among these changes. Recommendations for further research include studying speech comprehension in complex conditions, including meaningful-connection spoken language, and tailoring clinical interventions based on patients' auditory processing and cognitive abilities along with their individual socioemotional demands.

The hidden effect of hearing acuity on speech recall, and compensatory effects of self-paced listening

OBJECTIVE

The purpose of this research was to determine whether negative effects of hearing loss on recall accuracy for spoken narratives can be mitigated by allowing listeners to control the rate of speech input.

DESIGN

Paragraph-length narratives were presented for recall under two listening conditions in a within-participants design: presentation without interruption (continuous) at an average speech-rate of 150 words per minute; and presentation interrupted at periodic intervals at which participants were allowed to pause before initiating the next segment (self-paced).

STUDY SAMPLE

Participants were 24 adults ranging from 21 to 33 years of age. Half had age-normal hearing acuity and half had mild- to-moderate hearing loss. The two groups were comparable for age, years of formal education, and vocabulary.

RESULTS

When narrative passages were presented continuously, without interruption, participants with hearing loss recalled significantly fewer story elements, both main ideas and narrative details, than those with age-normal hearing. The recall difference was eliminated when the two groups were allowed to self-pace the speech input.

CONCLUSION

Results support the hypothesis that the listening effort associated with reduced hearing acuity can slow processing operations and increase demands on working memory, with consequent negative effects on accuracy of narrative recall.

Task-dependent organization of brain regions active during rest

The human brain demonstrates complex yet systematic patterns of neural activity at rest. We examined whether functional connectivity among those brain regions typically active during rest depends on ongoing and recent task demands and individual differences. We probed the temporal coordination among these regions during periods of language comprehension and during the rest periods that followed comprehension. Our findings show that the topography of this "rest network" varies with exogenous processing demands. The network encompassed more highly interconnected regions during rest than during listening, but also when listening to unsurprising vs. surprising information. Furthermore, connectivity patterns during rest varied as a function of recent listening experience. Individual variability in connectivity strength was associated with cognitive function: more attentive comprehenders demonstrated weaker connectivity during language comprehension, and a greater differentiation between connectivity during comprehension and rest. The regions we examined have generally been thought to form an invariant physiological and functional network whose activity reflects spontaneous cognitive processes. Our findings suggest that their function extends beyond the mediation of unconstrained thought, and that they play an important role in higher-level cognitive function.

Influence of text type, topic familiarity, and stuttering frequency on listener recall, comprehension, and mental effort

PURPOSE

To determine how text type, topic familiarity, and stuttering frequency influence listener recall, comprehension, and perceived mental effort.

METHOD

Sixty adults listened to familiar and unfamiliar narrative and expository texts produced with 0%, 5%, 10%, and 15% stuttering. Participants listened to 4 experimental text samples at only 1 stuttering frequency. After hearing the text samples, each listener performed a free recall task, answered cued recall questions, answered story comprehension questions, and rated their perceived mental effort.

RESULTS

Free and cued recall as well as story comprehension scores were higher for narrative than for expository texts. Free and cued recall scores were better for familiar than for unfamiliar stories, although topic familiarity did not affect story comprehension scores. Samples with all levels of stuttering resulted in higher mental effort ratings for both text types and topic familiarities.

CONCLUSIONS

Stuttering has a greater influence on listener recall and comprehension for narrative than for expository texts. Topic familiarity affects free and cued recall but has no influence on story comprehension. Regardless of the amount of stuttering, mental effort was high for both text types and levels of familiarity.

Auditory-visual discourse comprehension by older and young adults in favorable and unfavorable conditions

This investigation examined how age and test condition affect one's ability to comprehend discourse passages, and determined whether age and test condition affect discourse comprehension and closed-set sentence recognition in a similar way. Young and older adults were tested with closed-set sentences from the newly-created build-a-sentence test (BAS) and a series of discourse passages in two audiovisual conditions: favorable, where the talker's head was clearly visible and the signal-to-babble ratio (SBR) was more optimal; and unfavorable, where the contrast sensitivity of the visual signal was reduced and the SBR was less optimal. The older participants recognized fewer words in the BAS than the young participants in both test conditions. Degrading the viewing and listening conditions led to a greater decline in their performance than in the young participants' performance. The older participants also did not perform as well at comprehending spoken discourse in the two test conditions. However, unlike the results from the BAS, the age difference for discourse comprehension was not exacerbated by unfavorable conditions. When attempting to comprehend discourse, older adults may draw upon verbal and cognitive abilities that are relatively insensitive to age.

Aging and self-regulated language processing

An adult developmental model of self-regulated language processing (SRLP) is introduced, in which the allocation policy with which a reader engages text is driven by declines in processing capacity, growth in knowledge-based processes, and age-related shifts in reading goals. Evidence is presented to show that the individual reader's allocation policy is consistent across time and across different types of text, can serve a compensatory function in relation to abilities, and is predictive of subsequent memory performance. As such, it is an important facet of language understanding and learning from text through the adult life span.

Why do older adults have difficulty following conversations?

Age-related declines in understanding conversation may be largely a consequence of perceptual rather than cognitive declines. B. A. Schneider, M. Daneman, D. R. Murphy, and S. Kwong-See (2000) showed that age-related declines in comprehending single-talker discourse could be eliminated when adjustments were made to compensate for the poorer hearing of older adults. The authors used B. A. Schneider et al.'s methodology to investigate age-related differences in comprehending 2-person conversations. Compensating for hearing difficulties did not eliminate age-related differences when the 2 talkers were spatially separated by 9 degrees or 45 degrees azimuth, but it did when the talkers' contributions came from one central location. These findings suggest that dialogue poses more of a problem for older than for younger adults, not because of the additional cognitive requirements of having to follow 2 talkers rather than 1, but because older adults are not as good as younger adults at making use of the auditory cues that are available for helping listeners perceptually segregate the contributions of 2 spatially separated talkers.

The role of CA3 hippocampal NMDA receptors in paired associate learning

The hippocampus is necessary for declarative memory in humans and episodic memory in rodents. Considerable current research is focused on the role of plasticity within specific subfields of the hippocampus. Here, using a viral vector to temporally control a focal deletion of the NR1 gene, we show that learning novel paired associations between specific cues and their context is dependent on CA3 NMDA receptors. Deletion of CA3 NR1 genes in <30% of the dorsal hippocampus was sufficient to disrupt new learning, whereas the same treatment does not prevent expression of previously acquired paired associates and does not affect the ability to discriminate contexts or paired associate learning when either the cues or the context is familiar. The findings suggest that CA3 NMDA receptors specifically support the encoding of new experiences to involve incidental and contingent associations.

Age-related impairments in the revision of syntactic misanalyses: effects of prosody

Two experiments examined whether young and older adults differ in comprehending sentences that contain temporary syntactic closure ambiguities. Experiment 1 examined age-related differences using the Auditory Moving Window (AMW) task, in which sentences were presented in a segment-by-segment self-paced fashion. Experiment 2 examined age-related differences using a sentence recall task, in which sentences were presented in their entirety. Sentences were constructed to have cooperating prosody (i.e., where prosody is consistent with the syntactic boundaries), baseline prosody (i.e., where prosody is ambiguous in the syntactically ambiguous region), and conflicting prosody (i.e., where cross-splicing relocates the prosodic phrase break at a misleading point in syntactic structure). The results showed that both young and older adults make comparable use of prosodic information to interpret temporary syntactic ambiguities, although younger adults may make use of this information more quickly than older adults. In addition, older adults appeared to be less able than young adults to revise initial syntactic misinterpretations caused by conflicting prosodic information. These results are interpreted with respect to age-related impairments in the allocation of working memory resources and inefficient inhibitory function during spoken language processing.

Listening to spoken text: adult age differences as revealed by self-paced listening

An experiment is reported in which young and older adults heard spoken narratives presented in a segment-by-segment fashion using the auditory moving window (AMW) technique. Participants were instructed to initiate the presentation of each segment at their own pace, their goal being to insure good comprehension of the main ideas of the narratives. The pattern of pause times across passages was compared for passages being heard for the first time (novel condition) or after the participants had heard the passages several times before (familiar condition). The analysis of participants' pause durations in pacing through the passages suggests that although young and older adults respond similarly at the textbase level of processing, older adults do not allocate additional resources at the start of a passage in order to develop a mental model of the narrative. This pattern differs from that typically found in reading time studies.

Sentence processing strategies in healthy seniors with poor comprehension: an fMRI study

We used fMRI to examine patterns of brain recruitment in 22 healthy seniors, half of whom had selective comprehension difficulty for grammatically complex sentences. We found significantly reduced recruitment of left posterolateral temporal [Brodmann area (BA) 22/21] and left inferior frontal (BA 44/6) cortex in poor comprehenders compared to the healthy seniors with good sentence comprehension, cortical regions previously associated with language comprehension and verbal working memory, respectively. The poor comprehenders demonstrated increased activation of left prefrontal (BA 9/46), right dorsal inferior frontal (BA 44/6), and left posterior cingulate (BA 31/23) cortices for the grammatically simpler sentences that they understood. We hypothesize that these brain regions support an alternate, nongrammatical strategy for processing complex configurations of symbolic information. Moreover, these observations emphasize the crucial role of the left perisylvian network for grammatically guided sentence processing in subjects with good comprehension.

Memory and encoding of spoken discourse following right hemisphere damage: evidence from the Auditory Moving Window (AMW) technique

We investigated the hypotheses that impaired discourse processing following right hemisphere damage is mediated by task difficulty and is associated with deficits in discourse encoding. Spoken discourse passages differing in contextual predictability were presented to right hemisphere-damaged (RHD) patients and to non-brain-damaged (NBD) controls for subsequent recall using the Auditory Moving Window paradigm. To manipulate processing difficulty, speech segments were of normal or accelerated speech rates. The recall results showed that RHD adults recalled less than NBD controls overall and failed to recall major idea units better than minor idea units for high predictability passages presented at accelerated speech rates. Both RHD patients and NBD controls failed to recall major idea units better than minor idea units for low predictability passages, regardless of speech rate. The encoding results showed that RHD adults were both slower overall and differentially slower than NBD controls when listening to accelerated passage segments. Taken together, the encoding and recall results are consistent with the view that extracting passage gist under difficult listening conditions is especially vulnerable for patients with right hemisphere strokes.