Monday, November 24, 2014
Estes, K. G., & Hurley, K. (2013). Infant‐directed prosody helps infants map sounds to meanings. Infancy, 18(5), 797-824.
Infant directed speech is an exaggerated and repetitive speaking style that adults use when addressing infants. This form of speech encompasses a higher pitch, greater pitch variation and longer durations of speech segments. Infant directed speech supports early language acquisition by helping infants break up the speech they hear into components and helps maintain infant attention. In this paper, the researchers examined how infant directed speech influences an infants’ ability to connect sounds with meanings, specifically words with objects.
In this study, 17-month-old infants were presented with pictures of a novel object while listening to a name for the object. The amount of time the child looked at the novel object was recorded. Typically, infants look at novel objects for a long time at first, but once they become familiar with the stimulus, they spend less time looking (i.e., they become habituated). This method is called a habituation word-learning task. In the first experiment, the infants heard adult directed speech, and in the second, infant-directed speech. A third experiment also used infant directed speech but included different examples of the same word being spoken (different pitch contours and durations of the same word).
The authors found that infants were able to learn the object-label associations when the stimuli were produced using infant directed speech. Infants’ word learning was improved when the labels were produced using infant directed speech that contained variability (Experiment 3). This suggests that infants form stronger associations between objects and their labels when the sound of the labels contains variability (altered pitch and duration for the same label) such as those produced in Experiment 3. This variability mimics the variability found in naturalistic speech and appears to be critical in an infant’s ability to learn new words.
Blogger: Monica DaSilva is completing her Masters of Science in Developmental Psychology in the Language and Working Memory Lab. Her work will examine how infant word learning is enhanced by prosodic cues in words (i.e., word stress).
Danahy Ebert, K., & Scott C. M. (2014). Relationships between narrative language samples and norm-referenced test scores in language assessments of school-age children. Language, Speech, and Hearing Services in Schools, 45, 337–350.
Speech-language pathologists rely on a number of tools to complete comprehensive assessments of language abilities in school-age children. Two types of tools are norm-referenced tests and criterion-referenced tests. Norm-referenced tests assess broad language skill and allow clinicians to determine the child’s level of ability by comparing his performance to scores from a large sample of other children. In contrast, criterion-referenced tests offer in-depth information about a smaller set of language skills, but use more naturalistic tasks, such as recounting a narrative.
This study compared the performance of school-age children on a variety of norm-referenced tests and narrative language samples. The authors found that performance on the two types of assessments was more closely related for younger children (6–8 years) than for older children (9–12 years). The study also examined the extent to which the tests agreed on which children where considered to be impaired. Agreement of identification rates between different norm-referenced tests and different aspects of the narrative language samples ranged from 37% to 77%. This showed that some children were identified by both tests, while others were only identified by one type of test.
The authors conclude that age must be considered when selecting criterion-referenced tests because different types of naturalistic language tasks are more appropriate for different ages. They also suggest that clinicians continue to use both types of testing in their assessments in order to gather a wealth of information about each child’s language ability.
Blogger: Laura Pauls, MCISc-SLP
Blogger: Laura Pauls, MCISc-SLP
Monday, October 6, 2014
Oller, D. K., Pearson, B. Z., & Cobo-Lewis, A. B. (2007). Profile effects in early bilingual language and literacy. Applied Psycholinguistics, 28 (2), 191-230.
English-speaking bilingual and monolingual children perform differently on language tests. The scores of the monolingual group are usually higher, though not always. The pattern of group differences could be related to the aspect of language being investigated, an idea investigated in this paper.
Data were reanalyzed from 620 children in 2nd and 5th grades collected as part of a broad-scale study of monolingual English and bilingual Spanish–English learners in Miami. Findings showed no group differences in basic reading (phonics) tasks, but lower oral vocabulary scores for the bilingual Spanish–English than monolingual English learners.
Oller et al. explained this pattern of findings in terms of the “distributed characteristic” of the bilinguals’ knowledge. For bilingual speakers, some vocabulary items may be experienced in one setting and one language while other items are experienced in another setting and the other language. For example, words like ‘sewing’ may be used at home in Spanish, whereas ‘recess’ may occur at school in English. There are so many words being encountered, that the frequency of hearing (at least some) words in both languages may be low. As a result, lexical knowledge is ‘distributed’ across both languages leading but vocabulary level remains lower than monolingual peers in each language.
In contrast, learning two languages requires bilingual children to learn all the phonics of each language. Still, the total number of phonemes across both languages will be small allowing for the child to have frequent experiences with all the phonemes of the languages. Phonemic knowledge, then, is not distributed, but the same across languages. As s result, bilingual and monolingual groups do not differ in phonological analysis skills such as those employed basic reading tasks.
These findings suggest that the distributed characteristic of bilinguals’ knowledge across two languages has important implications for their language and literacy abilities.
Blogger: Areej Balilah.
Wednesday, June 18, 2014
Marton, K., Campanelli, L., Scheuer, J., Yoon, J., & Eichorn, N. (2012). Executive function profiles in children with and without Specific Language Impairment. Journal of Applied Psycholinguistics 12(3), 57–73.
Children with an unexpected delay in developing language known as specific language impairment (SLI) have been found to be less accurate on slower in performing a variety of cognitively demanding tasks. This paper investigates the hypothesis that these impairments result from deficits in executive functions, particularly working memory, inhibition, and sustained attention. Inhibition refers to the ability to ignore distracting information (“resistance to interference”), and to prevent previous tasks or routines from interfering with performance on new tasks (“inhibition of prepotent response”).
In this study, children with SLI and groups matched on age and language completed tests of visuospatial short term memory, resistance to interference, inhibition of prepotent response, and sustained attention. The SLI group performed more poorly than age-matched peers on the visuospatial short term memory and resistance to interference. Findings for the sustained attention task were mixed with no differences in the ability of the SLI group to identify correct sequences, but significantly poorer ability to reject incorrect sequences. No group differences were found in the task measuring inhibition of prepotent response.
These researchers provide a theoretically motivated evaluation of executive functions in SLI. One challenge in comparing the results to other studies with the same purpose is that these studies tend to adopt a variety of theoretical perspective and tasks. Further research is needed to examine the role of linguistic and cognitive factors across participant groups and tasks.
Blogger: Laura Pauls is a doctoral student in the LWM lab, and has completed her MClSc in speech language pathology.
Friday, May 23, 2014
Jaeggi, S.M., Buschkuehl, M., Perrig, W. J., & Meier, B. (2010). The concurrent validity of the N-back task as a working memory measure. Memory, 18, 4, 394-412. doi: http://dx.doi.org/10.1080/09658211003702171.
This article presents psychometric properties—reliability and concurrent validity—of the n-back task to assess working memory (WM) and other aspects of cognition such as executive functions (EF) and fluid intelligence (Gf). In the n-back task, the participant views or hears items in a sequence with items occasionally repeating. The participant is asked whether a current item is the same as the one presented ‘n’ back. So, in a 1-back task, the person judges if the item is the same as the one before; in a 2-back task, the person judges if the item is the same as the one before the one that was just shown (i.e., 2-items ago), etc. You can try a n-back task at this website: http://cognitivefun.net/test/4.
The n-back task is frequently used in neuroimaging studies and sometimes is considered a “pure” WM measure. However, not all of the previous evidence show strong links between n-back performance and scores on other measures commonly used to assess working memory such as simple or complex span tasks. In a simple span task, a person recalls the list of items presented such as repeating a list of digits. In a complex span, the person must manipulate the items in the list in some way (i.e., make a judgment about the item), and then recall items. Stronger associations have been found between the n-back and measures of executive functions and fluid intelligence.
In this paper, three experiments were conducted to further examine the reliability of the n-back task by measuring performance in 1-, 2-, and 3-back tasks, simple and complex span tasks, and EF and Gf. Overall, the n-task was moderately reliable based on split-half correlations comparing odd and even items (correlation range: 0.11 to 0.94). Reaction time (RT) was more reliable than accuracy, and the 2-back was more reliable than 1- and 3-back. The empirical results also confirmed previous findings of poor association between n-back and complex span tasks, but moderate correlation with simple span tasks. The test correlated poorly with EF, however it presented moderate-to-high correlations with Gf.
Although n-back and complex span tasks are considered to measure working memory, the tasks demands differ with n-back tasks requiring more continuous performance and attentional control and complex span tasks being more self-paced and self-ordered. It may be that the n-back and complex span tasks explain different parts of the variance in Gf. Caution is warranted in the use and interpretation of the n-back task.
Blogger: Alberto Filgueiras is a visiting doctoral student to the LWM lab from the Pontifical Catholic University of Rio de Janeiro, Brazil.
Monday, May 5, 2014
Barkley, R. (2012). Executive functions: what they are, how they work, and why they evolved. New York: Guilford press.
The focus of this text is to provide an understanding of both the how and why of executive functions. Barkley suggests that executive functions evolved to solve social problems. According to this view, there is a daily need to look ahead and anticipate what others are likely to do in the context of pursuing one’s own self-interests. Executive functions are seen as comprising both ‘cold’ cognitive functions of ‘what, where, and when’, as well as ‘hot’ cognitive or motivational functions of ‘why’. One key to the development of executive functions is the ability to create internal representations of stimuli that are no longer present. With these internalized representations, we can create a conscious mental life capable of imagining a hypothetical future. As we become self-aware, we shift our motivations towards attaining a goal, that is, a hypothetical future of our imagining. Using self-directed private speech, we coach ourselves through the actions necessary to achieve that goal. Barkley argues that one of the most distinctive features characterizing executive function impairments is the social disability arising due to a failure to act insightfully in the social context while pursuing a future goal.
The ideas described in this text have important clinical implications. The emphasis on both the individual’s motivations as well as cognitive abilities in setting future goals and plans is important. It calls for a need to consider an individual’s reason to pursue a goal as well as their ability to select and pursue that goal.
Blogger: Lisa Archibald