Why do older adults have difficulty with semantic fluency?

Aging involves many cognitive declines, particularly in fluid intelligence, with relative maintenance of crystallized intelligence. This paradox is evident in the language domain: lexical retrieval becomes slower and less accurate, despite well preserved vocabularies. Verbal fluency assesses both crystallized and fluid aspects of language. Semantic fluency hypothetically reflects semantic knowledge, while letter fluency putatively reflects executive functioning, which would predict a greater impact of aging on the latter. However, the opposite is typically observed.

To investigate factors contributing to such asymmetries, we examined verbal fluency in 86 adults (30-89 years). Multiple regression analyses indicated that semantic fluency depends largely on lexical retrieval speed, as well as visualization strategies to support controlled retrieval, skills which may disproportionately decline with age. By contrast, letter fluency relies heavily on vocabulary knowledge, providing some protection against age-related declines. These findings contribute to our understanding of the mechanisms of typical age-related declines in word retrieval.     

The oral and written side of word production in young and older adults: generation of lexical neighbors

The aim of the present study was to investigate the effects of aging on both spoken and written word production by using analogous tasks. To do so, a phonological neighbor generation task (Experiment 1) and an orthographic neighbor generation task (Experiment 2) were designed. In both tasks, young and older participants were given a word and had to generate as many words as they could think of by changing one phoneme in the target word (Experiment 1) or one letter in the target word (Experiment 2). The data of the two experiments were consistent, showing that the older adults generated fewer lexical neighbors and made more errors than the young adults. For both groups, the number of words produced, as well as their lexical frequency, decreased as a function of time. These data strongly support the assumption of a symmetrical age-related decline in the transmission of activation within the phonological and orthographic systems.     

中性抽象词和具体词情绪信息获得的差异

采用词汇迫选学习范式考察不同类型词汇获得情绪信息的认知机制。结果发现：（1）在迫选过程中与积极图片匹配的具体词汇喜好度显著高于与消极图片匹配的喜好度,而抽象词学习并未表现出这样的效应。（2）积极图片下被选择词汇的喜好度显著高于未被选择词汇的喜好度,而消极图片下被选择词汇与未被选择词汇的喜好度差异不显著。该结果表明具体词相较于抽象词更易获得相应情绪信息,积极情绪比消极情绪信息更易被习得。     

Size matters: Bigger is faster

A largely unexplored aspect of lexical access in visual word recognition is “semantic size”—namely, the real-world size of an object to which a word refers. A total of 42 participants performed a lexical decision task on concrete nouns denoting either big or small objects (e.g., bookcase or teaspoon). Items were matched pairwise on relevant lexical dimensions. Participants' reaction times were reliably faster to semantically “big” versus “small” words. The results are discussed in terms of possible mechanisms, including more active representations for “big” words, due to the ecological importance attributed to large objects in the environment and the relative speed of neural responses to large objects.     

Early use of phonetic information in spoken word recognition: Lexical stress drives eye movements immediately

For optimal word recognition listeners should use all relevant acoustic information as soon as it comes available. Using printed-word eye tracking we investigated when during word processing Dutch listeners use suprasegmental lexical stress information to recognize words. Fixations on targets such as “OCtopus” (capitals indicate stress) were more frequent than fixations on segmentally overlapping but differently stressed competitors (“okTOber”) before segmental information could disambiguate the words. Furthermore, prior to segmental disambiguation, initially stressed words were stronger lexical competitors than noninitially stressed words. Listeners recognize words by immediately using all relevant information in the speech signal.     

Executive processes in visual and spatial working memory tasks

Three experiments are reported, which have investigated the nature of the cognitive mechanisms that underlie performance on specific visuo-spatial working memory tasks, with the emphasis on exploring the extent of central executive involvement. Experiments 1 and 2 employed oral random digit generation as an executive task within a dual-task paradigm. The results of both experiments indicated that visuo-spatial tasks that involve sequential processing of information show more interference with random digit generation than do visuo-spatial tasks that involve simultaneous processing. The third experiment substituted oral random digit generation for executive tasks that did not involve memory for serial order (vigilance tasks adapted from Vandierendonck, De Vooght, & Van der Goten, 1998b). The results indicated significant interference between the vigilance tasks and the sequential visuo-spatial task, but not with the simultaneous visuo-spatial task. Overall the results of the three experiments are interpreted as indicating that serial sequential visuo-spatial tasks involve executive resources to a significantly greater extent than do simultaneous visuo-spatial tasks, and that this can have implications for studies that attempt to make use of such tasks to fractionate separable visual and spatial components within working memory.     

How strongly do word reading times and lexical decision times correlate? Combining data from eye movement corpora and megastudies

We assess the amount of shared variance between three measures of visual word recognition latencies: eye movement latencies, lexical decision times, and naming times. After partialling out the effects of word frequency and word length, two well-documented predictors of word recognition latencies, we see that 7–44% of the variance is uniquely shared between lexical decision times and naming times, depending on the frequency range of the words used. A similar analysis of eye movement latencies shows that the percentage of variance they uniquely share either with lexical decision times or with naming times is much lower. It is 5–17% for gaze durations and lexical decision times in studies with target words presented in neutral sentences, but drops to 0.2% for corpus studies in which eye movements to all words are analysed. Correlations between gaze durations and naming latencies are lower still. These findings suggest that processing times in isolated word processing and continuous text reading are affected by specific task demands and presentation format, and that lexical decision times and naming times are not very informative in predicting eye movement latencies in text reading once the effect of word frequency and word length are taken into account. The difference between controlled experiments and natural reading suggests that reading strategies and stimulus materials may determine the degree to which the immediacy-of-processing assumption and the eye–mind assumption apply. Fixation times are more likely to exclusively reflect the lexical processing of the currently fixated word in controlled studies with unpredictable target words rather than in natural reading of sentences or texts.     

Markedness effects in Norwegian–English bilinguals: Task-dependent use of language-specific letters and bigrams

This study investigates how bilinguals use sublexical language membership information to speed up their word recognition process in different task situations. Norwegian–English bilinguals performed a Norwegian–English language decision task, a mixed English lexical decision task, or a mixed Norwegian lexical decision task. The mixed lexical decision experiments included words from the nontarget language that required a “no” response. The language specificity of the Bokmål (a Norwegian written norm) and English (non)words was varied by including language-specific letters (“smør”, “hawk”) or bigrams (“dusj”, “veal”). Bilinguals were found to use both types of sublexical markedness to facilitate their decisions, language-specific letters leading to larger effects than language-specific bigrams. A cross-experimental comparison indicates that the use of sublexical language information was strategically dependent on the task at hand and that decisions were based on language membership information derived directly from sublexical (bigram) stimulus characteristics instead of indirectly via their lexical representations. Available models for bilingual word recognition fail to handle the observed marker effects, because all consider language membership as a lexical property only.     

Phonological and orthographic overlap effects in fast and masked priming

We investigated how orthographic and phonological information is activated during reading, using a fast priming task, and during single-word recognition, using masked priming. Specifically, different types of overlap between prime and target were contrasted: high orthographic and high phonological overlap (track–crack), high orthographic and low phonological overlap (bear–gear), or low orthographic and high phonological overlap (fruit–chute). In addition, we examined whether (orthographic) beginning overlap (swoop–swoon) yielded the same priming pattern as end (rhyme) overlap (track–crack). Prime durations were 32 and 50?ms in the fast priming version and 50?ms in the masked priming version, and mode of presentation (prime and target in lower case) was identical. The fast priming experiment showed facilitatory priming effects when both orthography and phonology overlapped, with no apparent differences between beginning and end overlap pairs. Facilitation was also found when prime and target only overlapped orthographically. In contrast, the masked priming experiment showed inhibition for both types of end overlap pairs (with and without phonological overlap) and no difference for begin overlap items. When prime and target only shared principally phonological information, facilitation was only found with a long prime duration in the fast priming experiment, while no differences were found in the masked priming version. These contrasting results suggest that fast priming and masked priming do not necessarily tap into the same type of processing.     

Time course analyses of orthographic and phonological priming effects during word recognition in a transparent orthography

In opaque orthographies, the activation of orthographic and phonological codes follows distinct time courses during visual word recognition. However, it is unclear how orthography and phonology are accessed in more transparent orthographies. Therefore, we conducted time course analyses of masked priming effects in the transparent Dutch orthography. The first study used targets with small phonological differences between phonological and orthographic primes, which are typical in transparent orthographies. Results showed consistent orthographic priming effects, yet phonological priming effects were absent. The second study explicitly manipulated the strength of the phonological difference and revealed that both orthographic and phonological priming effects became identifiable when phonological differences were strong enough. This suggests that, similar to opaque orthographies, strong phonological differences are a prerequisite to separate orthographic and phonological priming effects in transparent orthographies. Orthographic and phonological priming appeared to follow distinct time courses, with orthographic codes being quickly translated into phonological codes and phonology dominating the remainder of the lexical access phase.