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Mark S Seidenberg

Publications and source records attributed to Mark S Seidenberg.

16 recordsLinked to original sources
PubMed2006

Deficits in achromatic phantom contour perception in poor readers.

In a previous study [Sperling, A. J., Lu, Z. L., Manis, F. R., & Seidenberg, M. S. (2003). Selective deficits in magnocellular processing: A "phantom contour" study. Neuropsychologia, 41, 1422-1429] we found that dyslexic children were relatively slower in processing achromatic phantom contours. The maximum temporal frequency at which they could identify achromatic phantom contours was correlated with reading ability and orthographic skill in particular. Here we investigated whether similar deficits could be identified in adults. Poor readers were chosen who scored below the 25th percentile on either a standardized test of word identification or nonword pronunciation. Good readers were chosen who scored above the 40th percentile on both reading tasks. We replicated the findings of the child study: poor readers had slower processing in the achromatic version of the task, but not in the chromatic version. Achromatic performance correlated with several measures of reading and reading-related skills, including exception word reading and phonological awareness. We discuss the possibility that the deficits may indicate impairment in noise exclusion that is more readily apparent at higher temporal frequencies.

Child, Preschool↗
PubMed2006

Motion-perception deficits and reading impairment: it's the noise, not the motion.

We tested the hypothesis that deficits on sensory-processing tasks frequently associated with poor reading and dyslexia are the result of impairments in external-noise exclusion, rather than motion perception or magnocellular processing. We compared the motion-direction discrimination thresholds of adults and children with good or poor reading performance, using coherent-motion displays embedded in external noise. Both adults and children who were poor readers had higher thresholds than their respective peers in the presence of high external noise, but not in the presence of low external noise or when the signal was clearly demarcated. Adults' performance in high external noise correlated with their general reading ability, whereas children's performance correlated with their language and verbal abilities. The results support the hypothesis that noise-exclusion deficits impair reading and language development and suggest that the impact of such deficits on the development of reading skills changes with age.

Adolescent↗
PubMed2005

Deficits in perceptual noise exclusion in developmental dyslexia.

We evaluated signal-noise discrimination in children with and without dyslexia, using magnocellular and parvocellular visual stimuli presented either with or without high noise. Dyslexic children had elevated contrast thresholds when stimuli of either type were presented in high noise, but performed as well as non-dyslexic children when either type was displayed without noise. Our findings suggest that deficits in noise exclusion, not magnocellular processing, contribute to the etiology of dyslexia.

Artifacts↗
PubMed2005

Semantic feature production norms for a large set of living and nonliving things.

Semantic features have provided insight into numerous behavioral phenomena concerning concepts, categorization, and semantic memory in adults, children, and neuropsychological populations. Numerous theories and models in these areas are based on representations and computations involving semantic features. Consequently, empirically derived semantic feature production norms have played, and continue to play, a highly useful role in these domains. This article describes a set of feature norms collected from approximately 725 participants for 541 living (dog) and nonliving (chair) basic-level concepts, the largest such set of norms developed to date. This article describes the norms and numerous statistics associated with them. Our aim is to make these norms available to facilitate other research, while obviating the need to repeat the labor-intensive methods involved in collecting and analyzing such norms. The full set of norms may be downloaded from www.psychonomic.org/archive.

Adult↗
PubMed2005

Imaging the past: neural activation in frontal and temporal regions during regular and irregular past-tense processing.

This article presents fMRI evidence bearing on dual-mechanism versus connectionist theories of inflectional morphology. Ten participants were scanned at 4 Tesla as they covertly generated the past tenses of real and nonce (nonword) verbs presented auditorily. Regular past tenses (e.g., walked, wugged) and irregular past tenses (e.g., took, slept) produced similar patterns of activation in the posterior temporal lobe in both hemispheres. In contrast, there was greater activation in left and right inferior frontal gyrus for regular past tenses than for irregular past tenses. Similar previous results have been taken as evidence for the dual-mechanism theory of the past tense (Pinker & Ullman, 2002). However, additional analyses indicated that irregulars that were phonologically similar to regulars (e.g., slept, fled, sold) produced the same level of activation as did regulars, and significantly more activation than did irregulars that were not phonologically similar to regulars (e.g., took, gave). Thus, activation patterns were predicted by phonological characteristics of the past tense rather than by the rule-governed versus exception distinction that is central to the dual-mechanism framework. The results are consistent with a constraint satisfaction model in which phonological, semantic, and other probabilistic constraints jointly determine the past tense, with different degrees of involvement for different verbs.

Acoustic Stimulation↗
PubMed2004

Limits on reacquisition of song in adult zebra finches exposed to white noise.

Zebra finches (Taeniopygia guttata) learn a specific song pattern during a sensitive period of development, after which song changes little or not at all. However, recent studies have demonstrated substantial behavioral plasticity in song behavior during adulthood under a range of conditions. The current experiment examined song behavior of adult zebra finches temporarily deprived of auditory feedback by chronic exposure to loud white noise (WN). Long-term exposure to continuous WN resulted in disruption of song similar to that observed after deafening. When auditory feedback was restored by discontinuing WN, birds were either tutored using tape-recorded playback or housed with adult conspecific tutors. No evidence of learning new tutor syllables was observed, and recovery of pre-WN song patterns was very limited after restoration of hearing. However, many birds did reacquire some aspects of their pretreatment song, suggesting an adult form of learning that may retain some of the initial aspects of sensorimotor acquisition of song in which vocalizations are shaped to match a stored template representation. The failure to learn novel song elements and the modest degree of recovery observed overall suggest a limit on plasticity in adult birds that have acquired species-typical song patterns and may reflect an important species difference between zebra finches and Bengalese finches.

Age Factors↗
PubMed2004

Variation among developmental dyslexics: evidence from a printed-word-learning task.

A word-learning task was used to investigate variation among developmental dyslexics classified as phonological and surface dyslexics. Dyslexic children and chronological age (CA)- and reading level (RL)-matched normal readers were taught to pronounce novel nonsense words such as veep. Words were assigned either a regular (e.g., "veep") or an irregular (e.g., "vip") pronunciation. Phonological dyslexics learned both regular and exception words more slowly than the normal readers and, unlike the other groups, did not show a regular-word advantage. Surface dyslexics also learned regular and exception words more slowly than the CA group, consistent with a specific problem in mastering arbitrary item-specific pronunciations, but their performance resembled that of the RL group. The results parallel earlier findings from Manis, Seidenberg, Doi, McBride-Chang, & Petersen [Cognition 58 (1996) 157-195] indicating that surface dyslexics and phonological dyslexics have a different profile of reading deficits, with surface dyslexics resembling younger normal readers and phonological dyslexics showing a specific phonological deficit. Models of reading and reading disability need to account for the heterogeneity in reading processes among dyslexic children.

Articulation Disorders↗
PubMed2004

Computing the meanings of words in reading: cooperative division of labor between visual and phonological processes.

Are words read visually (by means of a direct mapping from orthography to semantics) or phonologically (by mapping from orthography to phonology to semantics)? The authors addressed this long-standing debate by examining how a large-scale computational model based on connectionist principles would solve the problem and comparing the model's performance to people's. In contrast to previous models, the present model uses an architecture in which meanings are jointly determined by the 2 components, with the division of labor between them affected by the nature of the mappings between codes. The model is consistent with a variety of behavioral phenomena, including the results of studies of homophones and pseudohomophones thought to support other theories, and illustrates how efficient processing can be achieved using multiple simultaneous constraints.

Humans↗
PubMed2004

Age-of-acquisition effects in reading aloud: tests of cumulative frequency and frequency trajectory.

Several studies have reported that the age at which a word is learned affects skilled reading. This age-of-acquisition effect is potentially important for theories of reading and learning. The effect has been difficult to pin down, however, because the age at which a word is learned is correlated with many other lexical properties. Zevin and Seidenberg (2002) analyzed these phenomena, using connectionist models that distinguished between cumulative frequency (the total number of times a word is experienced) and frequency trajectory (the distribution of these experiences over time). The models prompted a reevaluation of the empirical literature on this topic. The present research tested and confirmed three behavioral predictions derived from these models. First, cumulative frequency has an impact on skilled word naming, more so than standard measures of frequency derived from such norms as those of Kucera and Francis (1967). Second, frequency trajectory affects age of acquisition: The timing of exposure to words affects how rapidly they are learned. However, frequency trajectory does not affect skilled reading aloud, because the consistencies in mapping between spelling and sound eventually wash out the effects of early differences in frequency of exposure. Thus, in skilled performance, the timing of exposure to words is less important than the amount of exposure. The results clarify the conditions under which age-dependent learning effects occur in reading aloud.

Adolescent↗
PubMed2003

Language learning and innateness: some implications of Compounds Research.

In noun compounds in English, the modifying noun may be singular (mouse-eater) or an irregularly inflected plural (mice-eater), but regularly inflected plurals are dispreferred (*rats-eater). This phenomenon has been taken as strong evidence for dual-mechanism theories of lexical representations, which hold that regular (rule-governed) and irregular (exception) items are generated by qualitatively different and innately specified mechanisms. Using corpus analyses, behavioral studies, and computational modeling, we show that the rule-versus-exceptions approach makes a number of incorrect predictions. We propose a new account in which the acceptability of modifiers is determined by a constraint satisfaction process modulated by semantic, phonological, and other factors. The constraints are acquired by the child via general purpose learning algorithms, based on noun compounds and other constructions in the input. The account obviates the regular/irregular dichotomy while simultaneously providing a superior account of the data.

Child↗
PubMed2003

Selective magnocellular deficits in dyslexia: a "phantom contour" study.

A technique by Rogers-Ramachandran and Ramachandran [Vis. Res. 38 (1998) 71-77] was adapted to evaluate magnocellular (M) and parvocellular (P) visual processing efficiency, with identical task structure, in normal and dyslexic children. A battery of phonological, orthographic and cognitive tasks was administered to assess reading ability and component reading skills in both groups. For the visual processing experiment, children identified shapes created by patterns of dots flickering in counter-phase. The dots were black and white in the M condition, versus isoluminant red and green in the P condition. A staircase procedure determined the children's threshold flicker rate for shape identification. Dyslexics displayed selectively slower visual processing in the M condition but not in the P condition. Across all subjects, performance in the M condition was correlated with measures of orthographic skill, consistent with previous findings linking M processing and orthographic skill. Within the dyslexic group, processing in the M condition was negatively correlated with level of phonological awareness. The results are not consistent with the argument that dyslexics with phonological impairments suffer from deficits across all sensory modalities, as those children with the poorest phonological awareness displayed magnocellular processing well within the normal range.

Adolescent↗
PubMed2003

Phonology and syntax in specific language impairment: evidence from a connectionist model.

Difficulties in resolving pronominal anaphora have been taken as evidence that Specific Language Impairment (SLI) involves a grammar-specific impairment. The present study explores an alternative view, that grammatical deficits in SLI are sequelae of impaired speech perception. This perceptual deficit specifically affects the use of phonological information in working memory, which in turn leads to poorer than expected syntactic comprehension. This hypothesis was explored using a connectionist model of sentence processing that learned to map sequences of words to their meanings. Anaphoric resolution was represented in this model by recognizing the semantics of the correct antecedent when a bound pronoun was input. When the model was trained on distorted phonological inputs-simulating a perceptual deficit-it exhibited marked difficulty resolving bound anaphors. However, many other aspects of sentence comprehension were intact; most importantly, the model could still resolve pronouns using gender information. In addition, the model's deficit was graded rather than categorical, as it was able to resolve pronouns in some sentences, but not in others. These results are consistent with behavioral data concerning syntactic deficits in SLI. The model provides a causal demonstration of how a perceptual deficit could give rise to grammatical deficits in SLI.

Child↗
PubMed2003

The brain makes a distinction between hard and easy stimuli: comments on Beretta et al.

The Beretta et al. study tested an invalid prediction concerning connectionist models of inflectional morphology and the study exhibits a confound between type of stimulus (regular, irregular) and processing difficulty (easy, hard) that invalidates their conclusions. Harder stimuli produced greater activation across a broader range of brain areas, as in previous studies, but the data have no bearing on the rules vs. connections debate.

Brain↗
PubMed2002

Theories of word naming interact with spelling-sound consistency.

In a previous study (E. Strain, K. Patterson, & M. S. Seidenberg, 1995), the authors concluded that word naming is characterized by an interaction between spelling-sound typicality and word imageability, thus implicating a role for word meaning in the naming process. J. Monaghan and A. W. Ellis (2002) reject E. Strain et al.'s conclusion, arguing that it is age of acquisition (AoA) and not imageability that interacts with spelling-sound typicality. In this article, the authors question their alternative interpretation (a) by raising a number of conceptual and methodological issues germane to this debate and (b) by presenting new data that confirm a significant interaction between spelling-sound typicality and imageability in word-naming latencies, an interaction that is reliable when word AoA is controlled in a regression analysis.

Adult↗