Aging and the Deletion Function of Inhibition

The present study was adapted from the sentence completion task of Hartman and Hasher (1991). We addressed the question raised by Burke (1997): are the age-related differences in priming effects found in that task better explained by deficits in explicit memory or by inefficient inhibitory mechanisms? In the study phase, older and younger adults read high cloze sentences ending with an expected or an unexpected final word. In the second phase, participants were asked to complete sentence frames with either the final word presented during the study phase (inclusion condition) or with another, new word (exclusion condition). The third phase was an indirect memory test of perceptual identification. Finally, we compared explicit memory for recalled and inhibited words in a recognition test. In perceptual identification by older adults, priming was equivalent for recalled and inhibited words, whereas in younger adults priming was higher for recalled than for inhibited words. In the explicit memory test, recognition scores were lower for inhibited words in both age groups. These results are consistent with the view of Hasher and Zacks (1988), who assume an age-related decline in the ability to suppress no-longer-relevant information     

Difficulty processing temporary syntactic ambiguities in Lewy body spectrum disorder

While grammatical aspects of language are preserved, executive deficits are prominent in Lewy body spectrum disorder (LBSD), including Parkinson’s disease (PD), Parkinson’s dementia (PDD) and dementia with Lewy bodies (DLB). We examined executive control during sentence processing in LBSD by assessing temporary structural ambiguities. Using an on-line word detection procedure, patients heard sentences with a syntactic structure that has high-compatibility or low-compatibility with the main verb’s statistically preferred syntactic structure, and half of the sentences were lengthened strategically between the onset of the ambiguity and its resolution. We found selectively slowed processing of lengthened ambiguous sentences in the PDD/DLB subgroup. This correlated with impairments on measures of executive control. Regression analyses related the working memory deficit during ambiguous sentence processing to significant cortical thinning in frontal and parietal regions. These findings emphasize the role of prefrontal disease in the executive limitations that interfere with processing ambiguous sentences in LBSD.     

Effect of focus on verbal working memory: Critical role of the focus word in reading

The effect of focus on working memory was investigated with the reading span test (RST). In two experiments, the span scores and the number of intrusion errors were compared between the focused RST the and the nonfocused RST. Focus word was defined as the most important word for comprehending a sentence. For the focused RST, the target word to be maintained was the focus word for the sentence. In the nonfocused RST, however, the target word was not the focus word for the sentence. The results of both experiments showed that RST span scores were higher for the focused RST than for the nonfocused RST, and intrusion errors were found to increase for the nonfocused RST. In Experiment 2, the effect of focus was compared between high-span and low-span subjects. An effect of sentence length was also investigated. The result showed that low-span subjects were more affected than were high-span subjects by whether the word to be remembered was the focus word. The effect of sentence length was not confirmed. These findings suggest that the low-span subjects had deficits in their ability to establish and/or inhibit mental focus when faced with conflict situations in reading.     

“Hunting with a knife and … fork”: Examining central coherence in autism,attention deficit/hyperactivity disorder,and typical development with a linguistic task

A local processing bias, referred to as “weak central coherence,” has been postulated to underlie key aspects of autism spectrum disorder (ASD). Little research has examined whether individual differences in this cognitive style can be found in typical development, independent of intelligence, and how local processing relates to executive control. We present a brief and easy-to-administer test of coherence requiring global sentence completions. We report results from three studies assessing (a) 176 typically developing (TD) 8- to 25-year-olds, (b) individuals with ASD and matched controls, and (c) matched groups with ASD or attention deficit/hyperactivity disorder (ADHD). The results suggest that the Sentence Completion Task can reveal individual differences in cognitive style unrelated to IQ in typical development, that most (but not all) people with ASD show weak coherence on this task, and that performance is not related to inhibitory control. The Sentence Completion Task was found to be a useful test instrument, capable of tapping local processing bias in a range of populations.     

Strategic value-directed learning and memory in Alzheimer's disease and behavioural-variant frontotemporal dementia

In healthy adults, the ability to prioritize learning of highly valued information is supported by executive functions and enhances subsequent memory retrieval for this information. In Alzheimer's disease (AD) and behavioural-variant frontotemporal dementia (bvFTD), marked deficits are evident in learning and memory, presenting in the context of executive dysfunction. It is unclear whether these patients show a typical memory bias for higher valued stimuli. We administered a value-directed word-list learning task to AD (n = 10) and bvFTD (n = 21) patients and age-matched healthy controls (n = 22). Each word was assigned a low, medium or high point value, and participants were instructed to maximize the number of points earned across three learning trials. Participants’ memory for the words was assessed on a delayed recall trial, followed by a recognition test for the words and corresponding point values. Relative to controls, both patient groups showed poorer overall learning, delayed recall and recognition. Despite these impairments, patients with AD preferentially recalled high-value words on learning trials and showed significant value-directed enhancement of recognition memory for the words and points. Conversely, bvFTD patients did not prioritize recall of high-value words during learning trials, and this reduced selectivity was related to inhibitory dysfunction. Nonetheless, bvFTD patients showed value-directed enhancement of recognition memory for the point values, suggesting a mismatch between memory of high-value information and the ability to apply this in a motivationally salient context. Our findings demonstrate that value-directed enhancement of memory may persist to some degree in patients with dementia, despite pronounced deficits in learning and memory.     

Neuropsychological differentiation of progressive aphasic disorders

The differentiation of subtypes of primary progressive aphasia (PPA) remains challenging. We aimed to identify optimum neuropsychological measures for characterizing PPA, to examine the relationship between behavioural change and subtypes of PPA and to determine whether characteristic profiles of language, working memory, and behavioural changes occur in PPA. Forty-seven patients with PPA and multi-domain Alzheimer's disease (AD) together with 19 age-matched controls underwent a large battery of working memory and language tests. We found that simple tasks of sentence ordering, narrative production, and buccofacial praxis were particularly useful in differentiating non-fluent/agrammatic variant PPA (nfvPPA) from other PPA subtypes, whereas a test of single word comprehension was useful in detecting semantic dementia (SD). No individual tests were discriminating for logopenic variant PPA (lvPPA) relative to nfvPPA. LvPPA and multidomain AD exhibited similar language profiles. A principal components analysis revealed that characteristic PPA profiles extended beyond the realms of language, in particular, the presence of apraxia in nfvPPA, behavioural changes in SD, and working memory deficits in lvPPA. These findings suggest that not all tests are equally discriminatory for PPA and highlight the importance of a test profile in differentiating PPA. These results also support the view that lvPPA is a focal form of AD and emphasize the difficulties classifying lvPPA.     

Older adults can inhibit high-probability competitors in speech recognition

Younger and older adults identified a series of target words spoken in sentence contexts from their onsets only (i.e., word-onset gating). Sentences were drawn from published norms so that the contextual probabilities of the final words were known. the target words were always the second most probable responses to the sentence contexts, and the probabilities of the target words and the most likely alternatives were systematically varied. Results showed that older adults required more word-onset information for correct recognition, and their responses were more affected by the probability of the occurrence of the target word, supporting previous suggestions that older listeners differentially rely on contextual support in spoken word recognition. Contrary to the Inhibition Hypothesis, however, that older adults have especial difficulty suppressing irrelevant information once it is activited, elders' ability to recognize the target was not particularly disrupted by the presence of a high-probability competitor.     

Aging and suppression: memory for previously relevant information.

In the 1st part of the experiment, older and younger adults read a series of high-cloze sentence frames, each missing its final word (e.g., "She ladled the soup into her____."). Subjects were instructed to predict the ending for each. For critical sentences, the predicted final word (bowl) was not shown. Instead, an unexpected but acceptable ending (lap) was provided as the target. On a subsequent indirect memory test in which subjects generated endings to medium-cloze sentences, older adults showed reliable retention of both the disconfirmed (bowl) and target (lap) endings. Younger adults showed retention of only the targets. Results are consistent with the Hasher and Zacks (1988) view that the impaired inhibitory mechanisms of older adults impede the abandonment of no-longer-relevant thoughts.     

Behavior-analytic research on dementia in older adults

It is estimated that 1 in 10 adults aged 65 years and older have been diagnosed with dementia, which is associated with numerous behavioral excesses and deficits. Despite the publication of a special section of the Journal of Applied Behavior Analysis (JABA) on behavioral gerontology (Iwata, 1986), there continues to be a paucity of behavior-analytic research with this population. This review compares the research published before and after the behavioral gerontology special section and evaluates the most recently published aging articles in JABA.     

Naturalistic memory in learning-disabled and skilled readers

Three experiments compared learning-disabled and skilled readers' performance on naturalistic memory measures, as well as investigated the relationship between memory performance on everyday and laboratory tasks. In Experiment 1, the laboratory task (sentence span task) and everyday memory measures were correlated moderately for both ability groups. Compared to skilled readers, disabled readers performed poorly on the sentence span task, and were less likely than skilled readers to remember information related to common objects and consequential events. Disabled readers were also less likely to rely on external prompts to help them recall everyday information. Experiment 2 extended the previous findings to older subjects and found that the majority of significant correlations between the laboratory (word span task) and everyday memory tasks were isolated to disabled readers. When compared to chronological-age-matched subjects, disabled readers were inferior in recency performance on the laboratory (word span) and natural serial recall (e.g., recall of U.S. presidents) tasks. Experiment 3 showed that under conditions that facilitate item accessibility, ability group differences in recall were comparable. Taken together, the findings indicate that disabled readers' memory deficits are pervasive across naturalistic and laboratory measures at the younger age, but these deficits diminish for older students. Further, the deficits that occur at the older age are due to problems in accessing knowledge.     

Sentence-final word completion norms for European Portuguese children and adolescents

This study presents a set of sentence contexts and their cloze probabilities for European Portuguese children and adolescents. Seventy-three sentence contexts (35 low- and 38 high-constraint sentence stems) were presented to 90 children and 102 adolescents. Participants were asked to complete the sentence contexts with the first word that came to mind. For each sentence context, responses were listed and cloze probabilities of the words that were chosen to complete the sentence context were computed. Additionally, idiosyncratic and invalid responses (structural and semantic errors) were analyzed. A high degree of consistency in responses among the two age samples (children and adolescents) was found, along with a decrease of idiosyncratic and invalid responses in older participants. These results shed light on age-related changes in the effects of linguistic context on word production, and also in knowledge’s representation. The full set of norms may be downloaded from http://brm.psychonomic-journals.org/content/supplemental.     

The relationship between phonological and morphological deficits in Broca's aphasia: further evidence from errors in verb inflection

A previous study of 10 patients with Broca's aphasia demonstrated that the advantage for producing the past tense of irregular over regular verbs exhibited by these patients was eliminated when the two sets of past-tense forms were matched for phonological complexity (Bird, Lambon Ralph, Seidenberg, McClelland, & Patterson, 2003). The interpretation given was that a generalised phonological impairment was central to the patients' language deficits, including their poor performance on regular past tense verbs. The current paper provides further evidence in favour of this hypothesis, on the basis of a detailed analysis of the errors produced by these same 10 patients in reading, repetition, and sentence completion for a large number of regular, irregular, and nonce verbs. The patients' predominant error types in all tasks and for all verb types were close and distant phonologically related responses. The balance between close and distant errors varied along three continua: the severity of the patient (more distant errors produced by the more severely impaired patients); the difficulty of the task (more distant errors in sentence completion>reading>repetition); the difficulty of the item (more distant errors for novel word forms than real verbs). A position analysis for these phonologically related errors revealed that vowels were most likely to be preserved and that consonant onsets and offsets were equally likely to be incorrect. Critically, the patients' errors exhibited a strong tendency to simplify the phonological form of the target. These results are consistent with the notion that the patients' relatively greater difficulty with regular past tenses reflects a phonological impairment that is sensitive to the complexity of spoken forms.     

Adult age differences in the effects of sentence context and stimulus degradation during visual word recognition

I investigated adult age differences in the efficiency of feature-extraction processes during visual word recognition. Participants were 24 young adults (M age = 21.0 years) and 24 older adults (M age = 66.5 years). On each trial, subjects made a word/nonword discrimination (i.e., lexical decision) regarding a target letter-string that was presented as the final item of a sentence context. The target was presented either intact or degraded visually (by the presence of asterisks between adjacent letters). Age differences in lexical decisions speed were greater for degraded targets than for intact targets, suggesting an age-related slowing in the extraction of feature-level information. For degraded word targets, however, the amount of performance benefit provided by the sentence context was greater for older adults than for young adults. It thus appears that an age-related deficiency at an early stage of word recognition is accompanied by an increased contribution from semantic context.     

Inhibitory control over no-longer-relevant information: Adult age differences

Hartman and Hasher (1991) used a garden-path task in which younger and older adults generated the final word for each of a series of high-cloze sentences. Under instructions to remember the final word, the experiment included critical sentences for which the generated word was replaced by a new, to-be-remembered target. Using an implicit priming task, the first experiment replicated a basic finding: Younger adults showed priming only for the target words, whereas older adults showed priming for both the generated and target words. Two experiments explored boundary conditions. One showed that an additional sentence that interpreted the new target word enabled older adults to narrow access to only the target word. The provision of additional time following the introduction of the new target word did not. Specific information, not more time, is required for inefficient inhibitory mechanisms to clear the recent past from memory.     

Aging, parafoveal preview, and semantic integration in sentence processing: Testing the cognitive workload of wrap-up

The current study investigated the degree to which semantic-integration processes ("wrap-up") during sentence understanding demand attentional resources by examining the effects of clause and sentence wrap-up on the parafoveal preview benefit (PPB) in younger and older adults. The PPB is defined as facilitation in processing word N + 1, based on information extracted while the eyes are fixated on word N, and is known to be reduced by processing difficulty at word N. Participants read passages in which word N occurred in a sentence-internal, clause-final, or sentence-final position, and a gaze-contingent boundary-change paradigm was used to manipulate the information available in parafoveal vision for word N + 1. Wrap-up effects were found on word N for both younger and older adults. Early-pass measures (first-fixation duration and single-fixation duration) of the PPB on word N + 1 were reduced by clause wrap-up and sentence wrap-up on word N, with similar effects for younger and older adults. However, for intermediate (gaze duration) and later-pass measures (regression-path duration, and selective regression-path duration), sentence wrap-up (but not clause wrap-up) on word N differentially reduced the PPB of word N + 1 for older adults. These findings suggest that wrap-up is demanding and may be less efficient with advancing age, resulting in a greater cognitive processing load for older readers. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Strategic control in word reading: evidence from speeded responding in the tempo-naming task

To investigate strategic control over response initiation in word reading, the authors introduce the tempo-naming task. Relative to baseline performance in the standard-naming task, participants were induced to respond with faster latencies, shorter durations, and lower levels of accuracy by instructing them to time response initiation with an experimentally controlled tempo. The tempo response cue attenuated stimulus effects, and as faster tempos reduced latencies, the number of spelling-sound errors remained constant, whereas the number of word, nonword, and articulatory errors increased. To explain these results, the authors propose input gain as a mechanism of control over processing speed. The experimenters sketch how input gain could account for the current results as well as for the results from stimulus-blocking experiments testing the route emphasis and time criterion hypotheses of strategic control.     

Inhibitory processes in young and older adults in a picture-word task

Abstract

The present study examines changes in healthy young and healthy older adults in the ability to inhibit partially activated information in a picture/word interference paradigm. On each trial, subjects received a cue (i.e., the word PICTURE or WORD) indicating which of two stimuli the subject should attend to in an upcoming picture/word display. the display always contained a superimposed picture and word (e.g., a picture of a DEER with the word TEA printed on it). Following display offset, and depending upon the initial precue, either a test picture (e.g., KETTLE) or a test word (e.g., MOOSE) was presented. the subject's task was to determine as quickly and as accurately as possible whether the test stimulus was related to the cued dimension of the earlier picture/word display. the speed to reject an unrelated test item (e.g., picture of a KETTLE when the precue was PICTURE) that was related to the ignored dimension of the picture/word display (e.g., the word TEA in the picture/word display) was used as an index of the efficiency of the inhibitory system. the results indicated that older adults had more difficulty than younger adults inhibiting a to-be-ignored word when it was related to a picture test item, but did not have more difficulty inhibiting a to-be-ignored picture when it was related to a word test item. the results indicate that an age-related deficit in the control of interfering information is dependent upon the fluency of the processing routes.     

Inhibitory neighbor priming effects in eye movements during reading

We report an eye movement experiment investigating whether prior processing of a word’s orthographic neighbor in a sentence influences subsequent word processing during reading. There was greater difficulty in early word processing when a target word’s neighbor rather than a control word appeared earlier in a sentence; this effect was uninfluenced by the relative lexical frequency of the word and its neighbor. We discuss this inhibitory neighbor priming effect in terms of competitive network models of word recognition and the process of lexical identification in the E-Z Reader model of oculomotor control (e.g., Reichle, Pollatsek, Fisher, & Rayner, 1998).     

Working memory, inhibitory control, and reading disability

The relationships among working memory, inhibitory control, and reading skills were studied in 966 individuals, 6—49 years old. In addition to a standardized measure of word recognition, they received a working memory (listening span) task in the standard, blocked format (three sets containing two-, three-, or four-item trials) or in a mixed format (three sets each containing two-, three-, and four-item trials) to determine whether scores derived from the standard format are influenced by proactive interference. Intrusion errors were investigated in order to determine whether deficits in working memory were associated with the access, deletion, or restraint functions of inhibitory control. The results indicated that deficits in working memory were characteristic of individuals with reading disabilities at all ages. These deficits may be associated with the access and restraint functions of inhibition. Working memory skills increased until the age of 19. The blocked format showed a gradual decline in adulthood whereas the mixed format did not. The different patterns suggest that the decline in working memory skills associated with aging may result from growing inefficiencies in inhibitory control, and not diminished capacity.     

The role of inhibition in the production of disfluencies

Disfluency is a common occurrence in speech and is generally thought to be related to difficulty in the production system. One unexplored issue is the extent to which inhibition is required to prevent incorrect speech plans from being articulated. Therefore, we examined disfluency production in participants with attention-deficit/ hyperactivity disorder (ADHD), which is linked to deficits in inhibitory function and response suppression (Nigg, 2001). Participants completed a sentence production task in which they were presented with two pictures and a verb and their task was to produce a sentence. If inhibition plays a role in preventing incorrect speech plans, we would expect ADHD participants to produce more repetition and repair disfluencies than would non-ADHD controls. The results showed that one subtype of ADHD (i.e., the combined) produced more repair disfluencies as task demands increased. We conclude that the production system relies on inhibitory control in order to prevent errors in language production.