Biomedical subjects

Björn Lidestam

Publications and source records attributed to Björn Lidestam.

4 recordsLinked to original sources

PubMed2006

Visual phonemic ambiguity and speechreading.

PURPOSE: To study the role of visual perception of phonemes in visual perception of sentences and words among normal-hearing individuals. METHOD: Twenty-four normal-hearing adults identified consonants, words, and sentences, spoken by either a human or a synthetic talker. The synthetic talker was programmed with identical parameters within phoneme groups, hypothetically resulting in simplified articulation. Proportions of correctly identified phonemes per participant, condition, and task, as well as sensitivity to single consonants and clusters of consonants, were measured. Groups of mutually exclusive consonants were used for sensitivity analyses and hierarchical cluster analyses. RESULTS: Consonant identification performance did not differ as a function of talker, nor did average sensitivity to single consonants. The bilabial and labiodental clusters were most readily identified and cohesive for both talkers. Word and sentence identification was better for the human talker than the synthetic talker. The participants were more sensitive to the clusters of the least visible consonants with the human talker than with the synthetic talker. CONCLUSIONS: It is suggested that ability to distinguish between clusters of the least visually distinct phonemes is important in speechreading. Specifically, it reduces the number of candidates, and thereby facilitates lexical identification.

Acoustic Stimulation↗

PubMed2006

Motivation and appraisal in perception of poorly specified speech.

Normal-hearing students (n = 72) performed sentence, consonant, and word identification in either A (auditory), V (visual), or AV (audiovisual) modality. The auditory signal had difficult speech-to-noise relations. Talker (human vs. synthetic), topic (no cue vs. cue-words), and emotion (no cue vs. facially displayed vs. cue-words) were varied within groups. After the first block, effects of modality, face, topic, and emotion on initial appraisal and motivation were assessed. After the entire session, effects of modality on longer-term appraisal and motivation were assessed. The results from both assessments showed that V identification was more positively appraised than A identification. Correlations were tentatively interpreted such that evaluation of self-rated performance possibly depends on subjective standard and is reflected on motivation (if below subjective standard, AV group), or on appraisal (if above subjective standard, A group). Suggestions for further research are presented.

Adult↗

PubMed2005

Bottom-up driven speechreading in a speechreading expert: the case of AA (JK023).

OBJECTIVE: This case study tested the threshold hypothesis (Rönnberg et al., 1998), which states that superior speechreading skill is possible only if high-order cognitive functions, such as capacious verbal working memory, enable efficient strategies. DESIGN: In a case study, a speechreading expert (AA) was tested on a number of speechreading and cognitive tasks and compared with control groups (z scores). Sentence-based speechreading tests, a word-decoding test, and a phoneme identification task were used to assess speechreading skill at different analytical levels. The cognitive test battery used included tasks of working memory (e.g., reading span), inference-making, phonological processing (e.g., rhyme-judgment), and central-executive functions (verbal fluency, Stroop task). RESULTS: Contrary to previous cases of extreme speechreading skill, AA excels on both low-order (phoneme identification: z = +2.83) and high-order (sentence-based: z = +8.12 and word-decoding: z = +4.21) speechreading tasks. AA does not display superior verbal inference-making ability (sentence-completion task: z = -0.36). Neither does he possess a superior working memory (reading span: z = +0.80). However, AA outperforms the controls on two measures of executive retrieval functions, the semantic (z = +3.77) and phonological verbal fluency tasks (z = +3.55). CONCLUSIONS: The performance profile is inconsistent with the threshold hypothesis. Extreme speechreading accuracy can be obtained in ways other than via well-developed high-order cognitive functions. It is suggested that AA's extreme speechreading skill, which capitalizes on low-order functions in combination with efficient central executive functions, is due to early onset of hearing impairment.

Adult↗

PubMed2002

Effects of displayed emotion on attitude and impression formation in visual speech-reading.

In two experiments on visual speech-reading, with a total of 132 normal-hearing participants, the effects of displayed emotion and task specificity on speech-reading performance, on attitude toward the task and on person impression were explored, as well as associations between speech-reading performance, attitude, and person impression. The results show that displayed emotion increased speech-reading performance and attitude ratings, and that the actor was perceived as more extraverted both when displaying emotions, and when his speech was high in specificity The main conclusion was that displayed emotion enhances speech-reading performance by providing information that is useful to the speech-reader.

Adult↗