Recall of order information by deaf signers: phonetic coding in temporal order recall

Effect of visual presentation format and recall direction on letter span and error patterns in Deaf signing and hearing adults

Deaf signers consistently show shorter memory spans than hearing nonsigners, but the scope and nature of this difference remain unclear. The present study tested whether Deaf signers are biased toward flexible use of visual aspects of linguistic items. Matched samples of adult Deaf signers (N = 33) and hearing nonsigners (N = 32) performed a letter-span task with visual serial presentation, to bias phonological processing, and a simultaneous presentation, to bias visuospatial processing. We also manipulated short-term memory by varying recall direction (forward, backward). Analyses revealed reduced spans for Deaf signers compared with hearing nonsigners, backward compared with forward recall, and sequential compared with simultaneous presentation. Item-level responses indicated that Deaf signers made more errors than hearing nonsigners across three error types. Deaf signers also showed reduced item position binding compared with hearing nonsigners, which indicates differences related to item order and sequencing in tasks with printed, linguistic stimuli. Deaf signers were the only group who demonstrated reduced omission errors when switching from sequential to simultaneous presentation, suggesting flexible processing mechanisms. No group differences were found for a secondary spatial span test, indicating the scope of group differences for ordered information was limited to verbal items. Overall, results are consistent with flexible use of different memory cues in Deaf signers. A core area for future research includes evaluating reduced activation of phonological representations of linguistic items in Deaf signers. These results amplify a novel M³ model approach for evaluating how errors contribute to short-term memory differences in Deaf signers.

Generating a lexicon without a language model: Do words for number count?

Homesigns are communication systems created by deaf individuals without access to conventional linguistic input. To investigate how homesign gestures for number function in short-term memory compared to homesign gestures for objects, actions, or attributes, we conducted memory span tasks with adult homesigners in Nicaragua, and with comparison groups of unschooled hearing Spanish speakers and deaf Nicaraguan Sign Language signers. There was no difference between groups in recall of gestures or words for objects, actions or attributes; homesign gestures therefore can function as word units in short-term memory. However, homesigners showed poorer recall of numbers than the other groups. Unlike the other groups, increasing the numerical value of the to-be-remembered quantities negatively affected recall in homesigners, but not controls. When developed without linguistic input, gestures for number do not seem to function as summaries of the cardinal values of the sets (four), but rather as indexes of items within a set (one-one-one-one).

Routes to short-term memory indexing: lessons from deaf native users of American Sign Language

Models of working memory (WM) have been instrumental in understanding foundational cognitive processes and sources of individual differences. However, current models cannot conclusively explain the consistent group differences between deaf signers and hearing speakers on a number of short-term memory (STM) tasks. Here we take the perspective that these results are not due to a temporal order-processing deficit in deaf individuals, but rather reflect different biases in how different types of memory cues are used to do a given task. We further argue that the main driving force behind the shifts in relative biasing is a consequence of language modality (sign vs. speech) and the processing they afford, and not deafness, per se.

Looking for an explanation for the low sign span. Is order involved?

Although signed and speech-based languages have a similar internal organization of verbal short-term memory, sign span is lower than word span. We investigated whether this is due to the fact that signs are not suited for serial recall, as proposed by Bavelier, Newport, Hall, Supalla, and Boutla (2008. Ordered short-term memory differs in signers and speakers: Implications for models of short-term memory. Cognition, 107, 433-459). We administered a serial recall task with stimuli in Italian Sign Language to 12 deaf people, and we compared their performance with that of twelve age-, gender-, and education-matched hearing participants who performed the task in Italian. The results do not offer evidence for the hypothesis that serial order per se is a detrimental factor for deaf participants. An alternative explanation for the lower sign span based on signs being phonologically heavier than words is considered.

Cognitive performance of young and elderly subjects on the free word recall memory test: effect of presentation order on recall order

The influence of aging on memory has been extensively studied, but the importance of short-term memory and recall sequence has not. The objective of the current study was to examine the recall order of words presented on lists and to determine if age affects recall sequence. Physically and psychologically healthy male subjects were divided into two groups according to age, i.e., 23 young subjects (20 to 30 years) and 50 elderly subjects (60 to 70 years) submitted to the Wechsler Adult Intelligence Scale-Revised and the free word recall test. The order of word presentation significantly affected the 3rd and 4th words recalled (P < 0.01; F = 14.6). In addition, there was interaction between the presentation order and the type of list presented (P < 0.05; F = 9.7). Also, both groups recalled the last words presented from each list (words 13-15) significantly more times 3rd and 4th than words presented in all remaining positions (P < 0.01). The order of word presentation also significantly affected the 5th and 6th words recalled (P = 0.05; F = 7.5) and there was a significant interaction between the order of presentation and the type of list presented (P < 0.01; F = 20.8). The more developed the cognitive functions, resulting mainly from formal education, the greater the cognitive reserve, helping to minimize the effects of aging on the long-term memory (episodic declarative).

Phonological awareness and short-term memory in hearing and deaf individuals of different communication backgrounds

Previous work in deaf populations on phonological coding and working memory, two skills thought to play an important role in the acquisition of written language skills, have focused primarily on signers or did not clearly identify the subjects' native language and communication mode. In the present study, we examined the effect of sensory experience, early language experience, and communication mode on the phonological awareness skills and serial recall of linguistic items in deaf and hearing individuals of different communicative and linguistic backgrounds: hearing nonsigning controls, hearing users of ASL, deaf users of ASL, deaf oral users of English, and deaf users of cued speech. Since many current measures of phonological awareness skills are inappropriate for deaf populations on account of the verbal demands in the stimuli or response, we devised a nonverbal phonological measure that addresses this limitation. The Phoneme Detection Test revealed that deaf cuers and oral users, but not deaf signers, performed as well as their hearing peers when detecting phonemes not transparent in the orthography. The second focus of the study examined short-term memory skills and found that in response to the traditional digit span as well as an experimental visual version, digit-span performance was similar across the three deaf groups, yet deaf subjects' retrieval was lower than that of hearing subjects. Our results support the claim (Bavelier et al., 2006) that lexical items processed in the visual-spatial modality are not as well retained as information processed in the auditory channel. Together these findings show that the relationship between working memory, phonological coding, and reading may not be as tightly interwoven in deaf students as would have been predicted from work conducted in hearing students.

Ordered short-term memory differs in signers and speakers: implications for models of short-term memory

Capacity limits in linguistic short-term memory (STM) are typically measured with forward span tasks in which participants are asked to recall lists of words in the order presented. Using such tasks, native signers of American Sign Language (ASL) exhibit smaller spans than native speakers ([Boutla, M., Supalla, T., Newport, E. L., & Bavelier, D. (2004). Short-term memory span: Insights from sign language. Nature Neuroscience, 7(9), 997-1002]). Here, we test the hypothesis that this population difference reflects differences in the way speakers and signers maintain temporal order information in short-term memory. We show that native signers differ from speakers on measures of short-term memory that require maintenance of temporal order of the tested materials, but not on those in which temporal order is not required. In addition, we show that, in a recall task with free order, bilingual subjects are more likely to recall in temporal order when using English than ASL. We conclude that speakers and signers do share common short-term memory processes. However, whereas short-term memory for spoken English is predominantly organized in terms of temporal order, we argue that this dimension does not play as great a role in signers' short-term memory. Other factors that may affect STM processes in signers are discussed.

Short-term memory span: insights from sign language

Short-term memory (STM), or the ability to hold information in mind for a few seconds, is thought to be limited in its capacity to about 7 +/- 2 items. Notably, the average STM capacity when using American Sign Language (ASL) rather than English is only 5 +/- 1 items. Here we show that, contrary to previous interpretations, this difference cannot be attributed to phonological factors, item duration or reduced memory abilities in deaf people. We also show that, despite this difference in STM span, hearing speakers and deaf ASL users have comparable working memory resources during language use, indicating similar abilities to maintain and manipulate linguistic information. The shorter STM span in ASL users therefore confirms the view that the spoken span of 7 +/- 2 is an exception, probably owing to the reliance of speakers on auditory-based rather than visually based representations in linguistic STM, and calls for adjustments in the norms used with deaf individuals.

Orthographic structure and deaf spelling errors: syllables, letter frequency, and speech

Syllable structure influences hearing students' reading and spelling (e.g., Badecker, 1996; Caramazza & Miceli, 1990; Prinzmetal, Treiman, & Rho, 1986; Rapp, 1992; Treiman & Zukowski, 1988). This may seem unsurprising since hearers closely associate written and spoken words. We analysed a corpus of spelling errors made by deaf students. They would have learned English orthography with an attenuated experience of speech. We found that the majority of their errors were phonologically implausible but orthographically legal. A tendency to replace uncommon letter sequences with common sequences could not account for this pattern, nor could residual influence from speech. Since syllabically defined constraints are required to keep sequences orthographically legal, the deaf data are marked by an influence of syllable structure. Two main conclusions follow: (1) Our results contribute to evidence that abstract constraints, not derived from peripheral speech or hearing mechanisms, govern the organization of linguistic knowledge; and (2) statistical redundancy could not explain the deaf results. It does not offer a general alternative to suprasegmental structure.

Exploring hypotheses about phonological awareness, memory, and reading achievement

Reading-related skills were tested in adults with and without reading disabilities (RD) and adults with profound hearing impairment (PHI) who did not differ on average Performance IQ. The RD group and the PHI group both demonstrated levels of phonological awareness lower than the control group's, but only the RD group also exhibited deficits in other skills, including verbal short-term memory, morphological awareness, speeded written naming, and reading comprehension. The average reading level of the PHI group was significantly higher than that of the RD group. Three control group members also demonstrated limited phonological awareness without other deficits in a pilot study, performing similarly to the PHI group. The results support other studies suggesting that processes dependent on memory, not solely phonological awareness, may contribute to determining reading achievement.

Some measures of verbal and spatial working memory in eight- and nine-year-old hearing-impaired children with cochlear implants

OBJECTIVE

The purpose of this study was to examine working memory for sequences of auditory and visual stimuli in prelingually deafened pediatric cochlear implant users with at least 4 yr of device experience.

DESIGN

Two groups of 8- and 9-yr-old children, 45 normal-hearing and 45 hearing-impaired users of cochlear implants, completed a novel working memory task requiring memory for sequences of either visual-spatial cues or visual-spatial cues paired with auditory signals. In each sequence, colored response buttons were illuminated either with or without simultaneous auditory presentation of verbal labels (color-names or digit-names). The child was required to reproduce each sequence by pressing the appropriate buttons on the response box. Sequence length was varied and a measure of memory span corresponding to the longest list length correctly reproduced under each set of presentation conditions was recorded. Additional children completed a modified task that eliminated the visual-spatial light cues but that still required reproduction of auditory color-name sequences using the same response box. Data from 37 pediatric cochlear implant users were collected using this modified task.

RESULTS

The cochlear implant group obtained shorter span scores on average than the normal-hearing group, regardless of presentation format. The normal-hearing children also demonstrated a larger "redundancy gain" than children in the cochlear implant group-that is, the normal-hearing group displayed better memory for auditory-plus-lights sequences than for the lights-only sequences. Although the children with cochlear implants did not use the auditory signals as effectively as normal-hearing children when visual-spatial cues were also available, their performance on the modified memory task using only auditory cues showed that some of the children were capable of encoding auditory-only sequences at a level comparable with normal-hearing children.

CONCLUSIONS

The finding of smaller redundancy gains from the addition of auditory cues to visual-spatial sequences in the cochlear implant group as compared with the normal-hearing group demonstrates differences in encoding or rehearsal strategies between these two groups of children. Differences in memory span between the two groups even on a visual-spatial memory task suggests that atypical working memory development irrespective of input modality may be present in this clinical population.

Perceiving imitatible stimuli: consequences of isomorphism between input and output

For more than a century, psychologists have been intrigued by the idea that mental representations of perceived human actions are closely connected with mental representations of performing those same actions. In this article, connections between input and output representations are considered in terms of the potential for imitation. A broad range of evidence suggests that, for imitatible stimuli, input and output representations are isomorphic to one another, allowing mutual influence between perception and motoric planning that is rapid, effortless, and possibly obligatory. Thus, the cognitive consequences of imitatibility may underlie such diverse phenomena as phoneme perception; imitation in neonates; echoic memory; stimulus-response compatibility; conduction aphasia; maintenance rehearsal; and a variety of developmental and social activities such as language acquisition, social learning, empathy, and monitoring one's own behavior.

Self-report measures among transplant candidates: the impact of evaluative situations

Experiment 1 was a between-subjects design comparing transplant candidates completing self-report measures under an evaluative versus an anonymous research condition. A cardiac disease group and a healthy community group served as controls. Transplant candidates in the anonymous research condition reported significantly more depression, anxiety, and negative affectivity as compared with transplant candidates in the evaluative condition and community controls. In contrast, the evaluative transplant group (a) did not differ from the community controls on any of the self-report measures, and (b) reported significantly less depression than cardiac disease controls. Experiment 2 was a within-subjects design with transplant candidates completing self-report measures under both an evaluative and an anonymous research condition. Significantly greater anxiety was reported under the anonymous research condition. Social desirability was significantly related to change in self-reported anxiety and depression across conditions, but was unrelated to change in endorsement of personality characteristics.

A "word length effect" for sign language: further evidence for the role of language in structuring working memory

We report a sign length effect in deaf users of American Sign Language that is analogous to the word length effect for speech. Lists containing long signs (signs that traverse relatively long distances) produced poorer memory performance than did lists of short signs (signs that do not change in location). Further, this length effect was eliminated by articulatory suppression (repetitive motion of the hands), and articulatory suppression produced an overall drop in performance. The pattern of results, together with previous findings (Wilson & Emmorey, 1997), provides evidence for a working memory system for sign language that consists of a phonological storage buffer and an articulatory rehearsal mechanism. This indicates a close equivalence of structure between working memory for sign language and working memory for speech. The implications of this equivalence are discussed.

A visuospatial "phonological loop" in working memory: evidence from American Sign Language

In two experiments, the question of whether working memory could support an articulatory rehearsal loop in the visuospatial domain was investigated. Deaf subjects fluent in American Sign Language (ASL) were tested on immediate serial recall. In Experiment 1, with ASL stimuli, evidence was found for manual motoric coding (worse recall under articulatory suppression) and previous findings of ASL-based phonological coding (worse recall for phonologically similar lists) were replicated [corrected]. The two effects did not interact, suggesting separate components which both contribute to performance. Stimuli in Experiment 2 were namable pictures, which had to be recoded for ASL-based rehearsal to occur. Under these conditions, articulatory suppression eliminated the phonological similarity effect. Thus, an articulatory process seems to be used in translating pictures into a phonological code for memory maintenance. These results indicate a configuration of components similar to the phonological loop for speech, suggesting that working memory can develop a language-based rehearsal loop in the visuospatial modality.