Models for letter cancellation performance and their implications for models of reading

Models for letter cancellation are developed, i.e. for tasks where subjects read a coherent piece of prose at the same time as trying to cancel every target letter they encounter. These models have two components (i) a model of how information is represented by the reader, (ii) a model of how this information is scanned to enable the reader to detect particular target letters. Models of representation range from a photographic image of the printed page to a sophisticated multi-level representation, and models of scanning range from a series of independent saccadic movements (like eye movements) to scans which take into account morphemic and syntactic structure.

Several predictions about the detailed pattern of letter cancellation data are developed on the basis of these models, and these are tested on a data base collected by Smith and Groat (1979). While some support for the simpler models is forthcoming, only the most elaborate models (multi-level representation, syntactically guided scan) can fully account for all the data. While instances can be found where the cancellation task is clearly disrupting the reading task, much of the data are consistent with the notion that the letter cancellation task is not excessively intrusive, and our analyses can thus give us significant information about normal reading.     

Speed of letter cancellation on the basis of visual and name identity in young children

Second-, fourth-, and sixth-grade children were tested on a visual search task where letter matching was based on the visual or name characteristics of letters. Visual match lists were searched faster than name match lists by all three grades. In the name match lists there was an increase in speed as a function of trials whereas in the visual match lists there was no increase. The name-physical match difference did not change as a function of age.     

Phonetic, phonemic, and phonological factors in cross-language discrimination of phonotactic contrasts

Previous research indicates that multiple levels of linguistic information play a role in the perception and discrimination of non-native phonemes. This study examines the interaction of phonetic, phonemic and phonological factors in the discrimination of non-native phonotactic contrasts. Listeners of Catalan, English, and Russian are presented with an initial #CC-#C?C contrast in a discrimination task. For the Catalan group, the phonemes and their phonetic implementation were native, but the #CC phonotactics were not. For Russian listeners, the phonemes and phonetic implementation were not native but Russian allows a large number of #CC sequences. For English listeners, none of the phonetics, phonemes, nor phonotactics are native. Two task variables, stimuli length and order of presentation, were also manipulated. Results showed that the Russian listeners were most accurate overall, suggesting that the presence of the phonotactic structure in the listeners' native language may be more important than either phonemic or phonetic information. The interaction between the task manipulations and the linguistic variables is also addressed.     

Some factors affecting tachistoscopic letter recognition

Summary The paper reports a series of studies that attempt to examine the issue of tachistoscopic identification of letter material. In particular a reductionist approach is used to investigate the influence of retinal locus, cerebral dominance, metacontrast, letter symmetry, and ocular dominance on the task. Retinal locus, metacontrast, and ocular dominance were shown to influence letter reportability under the present conditions with, it is argued, retinal locus and metacontrast affecting the integrity of the icon. Evidence is given for the construct of ocular dominance as the eye (dominant) initiating eye movements with the other passively following.     

Phonetic factors in letter detection: A reevaluation

Three experiments in which subjects searched for the letter e in printed text were conducted to examine the effects of phonetic factors in silent reading. In Experiment 1, subjects made more errors on silent es than on pronounced es, but silent es always occurred at the ends of words, whereas pronounced es occurred in the middle of words. In Experiment 2, all instances of the letter e occurred in the penultimate location in the words, and no effects of letter voicing were obtained. In Experiment 3, subjects made more errors on es in unstressed syllables than on es in stressed syllables in three-syllable words. However, this effect occurred only for es in the second and third syllables and only for the more common words. All three experiments yielded large effects of word frequency, which were reduced in passages printed in alternating typecase. It was concluded that letter detection is affected by syllable stress but not by letter voicing and that the stress effect depends on whether the subject is able to form reading units at the syllable level.     

Spectral fissioning in phonemic transformations

Listeners presented with a repeated sequence of brief (30- to 100-msec) steady-state vowels hearphonemic transformations—they cannot identify the vowels, but they perceive two simultaneous utterances that differ in both phonemic content and timbre (Warren, Bashford, & Gardner, 1990). These utterances consist of either English words or syllables that occur in English words. In the present study, we attempted to determine whether the two percepts represent alternative interpretations of the same formant structures, or whether different portions of the vowels are used for each verbal organization. It was found that separate spectral regions are employed for each verbal form; Components below 1500 Hz were generally used for one form, and components above 1500 Hz for the other. Hypotheses are offered concerning the processes responsible for the verbal organization of the vowel sequences and for the splitting into two spectrally limited forms. It appears that the tendency to organize spectral regions separately competes with, and can overcome, the tendency to integrate the different spectral components of speech into a single auditory image. A contralateral induction paradigm was used in a procedure designed to quantitatively evaluate these opposing forces of spectral fission and fusion.     

Speech perception and phonemic restorations

When a speech sound in a sentence is replaced completely by an extraneous sound (such as a cough or tone), the listene restores the missing sound on the bases of both prior and subsequent context. This illusory effect, called phonemic restoration (PhR), causes the physically absent phoneme to seem as real as the speech sounds which are present. The extraneous sound seems to occur along with other phonemes without interfering with their clarity. But if a silent gap (rather than an extraneous sound) replaces the same phoneme, the interruption in the sentence is more readily localized in its true position and PhRs occours less frequently. Quantitative measures were taken both of the incidence of PhRs and of the direction and extent of temporal mislocalizations of interruptions for several related stimuli under a variety of experimental conditions. The results were connected with other auditory illusions and temporal confusions reported in the literature, and suggestions were made concerning mechanisms employed normally for verbal organization.     

Sequences of phonemic approximations in aphasia

The trends of sequences of phonemic approximations to a single target were studied in three types of aphasia (Broca's, conduction, and Wernicke's), as gathered in five tasks (spontaneous speech, repetition of meaningful words, repetition of nonsense words, reading aloud, and automatized sequences). A phonemic error ratio was defined in order to quantify the distance between each approximation of a given sequence and its target. The results of a computer analysis based on this ratio were analyzed according to three parameters. A study of three types of patients revealed that conduction aphasics exhibited the most regular trend toward the target in sequences of phonemic approximations; the analysis of the various tasks indicated that sequences produced in repetition by conduction aphasics form an exception to the regularity of this trend, and an examination of the various lengths of sequences indicated that longer sequences showed a less decisive trend toward the target than shorter sequences. The discussion bears on some theoretical aspects of the phonological production mechanism and its control: the initial strength and permanence of the internal representation of the target emerge as important factors required for the good functioning of this mechanism.     

Selective phonemic and semantic coding in short-term recall

Probed recall of targets from six-word sequences containing either phonemically similar, semantically similar, or control (i.e., unrelated phonemically and semantically) stimuli was compared under two conditions of encoding. For the semantic encoding condition, in which all cues provided category information about targets to be recalled, semantic similarity interference effects and phonemic similarity facilitation effects were demonstrated. In the phonemic encoding condition, in which all targets were cued by words which rhymed with them, only phonemic similarity interference effects were found. These results were taken to provide further evidence contradictory to the coding-based dichotomization of primary and secondary memory, and to reflect the importance of selective coding strategies induced by task requirements as determinants of interference effects in short-term recall.     

Auditory word comprehension impairment in acute stroke: relative contribution of phonemic versus semantic factors

Auditory word comprehension was assessed in a series of 289 acute left hemisphere stroke patients. Participants decided whether an auditorily presented word matched a picture. On different trials, words were presented with a matching picture, a semantic foil, or a phonemic foil. Participants had significantly more trouble with semantic foils across all levels of impairment.     

Rhyme recognition and phonemic perception in young children

A forced-choice rhyme recognition test was used to assess the ability of 4-,5-, and 6-year-old children to recognize rhymes. The number and position of phonemes shared by the rhyming and nonrhyming response choices were systematically varied. Although there were age differences, the performance levels were quite high for all age groups, including the 4-year-olds. For all age groups, formal similarity of the stimulus word and nonrhyming choice proved to be a major factor determining the difficulty of rhyming items. The results were discussed in terms of potential implications for improving reading readiness.This paper is based on an M.A. thesis conducted by the first author under the direction of the second author. Funds for the purchase of computer time were made available by the Graduate College, University of Iowa.     

Nonstrategic subjective threshold effects in phonemic masking

Three backward-masking experiments demonstrated that the magnitude of the phonemic mask reduction effect (MRE) is a function of subjective threshold and that the magnitude is also independent of stimulus-based response strategies. In all three experiments, a target word (e.g., bake) was backward masked by a graphemically similar nonword (e.g., BAWK), a phonemically similar nonword (e.g., BAIK), or an unrelated control (e.g., CRUG). Experiments 1 and 2 had a low percentage (9%) of trials with phonemic masks and differed only in baseline identification rate. Experiment 3 controlled baseline identification rate at below and above subjective threshold levels, with 9% phonemic trials. The results were that identification rates were higher with phonemic masks than with graphemic masks, irrespective of the low percentage of phonemic trials. However, the magnitude of the phonemic MRE became large only when the baseline identification rate was below subjective threshold. The pattern of the phonemic MRE was interpreted as a result of rapid automatic phonological activation, independent of stimulus-based processing strategies.     

Overwriting of phonemic features in serial recall

We tested two explanations of the phonological similarity effect in verbal short‐term memory: The confusion hypothesis assumes that serial positions of similar items are confused. The overwriting hypothesis states that similar items share feature representations, which are overwritten. Participants memorised a phonologically dissimilar list of CVC‐trigrams (Experiment 1) or words (Experiment 2 and 3) for serial recall. In the retention interval they read aloud other items. The material of the distractor task jointly overlapped one item of the memory list. The recall of this item was impaired, and the effect was not based on intrusions from the distractor task alone. The results provide evidence for feature overwriting as one potential mechanism contributing to the phonological similarity effect.     

Overwriting of phonemic features in serial recall

We tested two explanations of the phonological similarity effect in verbal short-term memory: The confusion hypothesis assumes that serial positions of similar items are confused. The overwriting hypothesis states that similar items share feature representations, which are overwritten. Participants memorised a phonologically dissimilar list of CVC-trigrams (Experiment 1) or words (Experiment 2 and 3) for serial recall. In the retention interval they read aloud other items. The material of the distractor task jointly overlapped one item of the memory list. The recall of this item was impaired, and the effect was not based on intrusions from the distractor task alone. The results provide evidence for feature overwriting as one potential mechanism contributing to the phonological similarity effect.     

Functions of graphemic and phonemic codes in visual word-recognition

Previous investigators have argued that printed words are recognized directly from visual representations and/or phonological representations obtained through phonemic recoding. The present research tested these hypotheses by manipulating graphemic and phonemic relations within various pairs of letter strings. Ss in two experiments classified the pairs as words or nonwords. Reaction times and error rates were relatively small for word pairs (e.g., BRIBE-TRIBE) that were both graphemically, and phonemically similar. Graphemic similarity alone inhibited performance on other word pairs (e.g., COUCH-TOUCH). These and other results suggest that phonological representations play a significant role in visual word recognition and that there is a dependence between successive phonemic-encoding operations. An encoding-bias model is proposed to explain the data.     

Word recognition in a phonemic dyslexic patient

The systems underlying word recognition were investigated in a single case study of a patient (K.F.) with an acquired dyslexia. His reading performance was related to parts of speech, word frequency and word concreteness, and his reading errors were analysed. There was a very striking difference between his ability to read concrete and abstract words. Furthermore visual errors, which could not be attributed to a deficit at a peripheral level, predominated; phonemic errors did not occur. It is argued that these findings support a dual encoding model of word recognition, the present case illustrating the impairment of the phonemic route, a direct graphemic-semantic route being relatively spared. These findings and interpretation are for the most part consistent with Marshall and Newcombe's (1973) studies of acquired dyslexia. The present findings are discussed in terms of more general theories of word recognition.     

Components of phonemic processing and the beginning reader

This study primarily investigated various aspects of phonemic processing and memory in relation to reading in 74 5- and 6-year-old British children. A principal components analysis revealed a major connection between reading and aspects of phonemic processing for both age groups. For the 5-year-olds the processing of the initial phoneme was important for reading, whereas for the 6-year-olds processing of initial and final phonemes appeared to be equally related on this factor. A second factor for both groups was intelligence, which was related to reading only for the 6-year-olds; but this intelligence factor was more associated with phonemic processing for the 5-year-olds. An analysis involving clustering individual readers with similar patterns across the experimental variables showed some consistent profiles for disabled readers across the two age groups. These profiles suggested potential areas for remediation according to subgroup membership.     

Contrasting speech patterns in apraxia of speech and phonemic paraphasia

This study was designed to determine if perceptual phonological analysis would reveal distinctions between patients with apraxia of speech and patients with phonemic paraphasic speech. Test findings from 10 Broca's aphasics with apraxia of speech were compared to findings from 10 paraphasic speakers (5 conduction and 5 Wernicke's aphasics). Several marked differences were revealed. Predominant locus of errors and relative difficulty of different classes of phonemic segments were significant discriminators. There was a nonsignificant trend for substituted phonemes to be further from target phonetically in the paraphasic patients. In addition, the two groups showed certain consistent differences in the types of errors they produced. Apraxic patients produced many errors of transitionalization, while sequencing errors were more typical of the patients with phonemic paraphasia. The findings are interpreted in relation to a neuropsychological model of speech. It is suggested that phonemic paraphasia represents a breakdown mainly in the retrieval of phonological word patterns, while apraxia of speech is characterized predominantly by a disturbance in encoding phonological patterns into appropriate speech movements.     

Components of phonemic processing and the beginning reader

This study primarily investigated various aspects of phonemic processing and memory in relation to reading in 74 5- and 6-year-old British children. A principal components analysis revealed a major connection between reading and aspects of phonemic processing for both age groups. For the 5-year-olds the processing of the initial phoneme was important for reading, whereas for the 6-year-olds processing of initial and final phonemes appeared to be equally related on this factor. A second factor for both groups was intelligence, which was related to reading only for the 6-year-olds; but this intelligence factor was more associated with phonemic processing for the 5-year-olds. An analysis involving clustering individual readers with similar patterns across the experimental variables showed some consistent profiles for disabled readers across the two age groups. These profiles suggested potential areas for remediation according to subgroup membership.     

Transient phonemic codes and immunity to proactive interference

Empirical data indicate that when memory for subspan lists of taxonomically related material is tested immediately after study, prior experience with lists involving the same material has no effect upon recall or recognition. In six experiments, we explored the possibility that immunity to proactive interference (PI) is related to discriminative information that is provided by transient phonemic codes. In these experiments, we manipulated the strength of phonemic codes as well as their presence or absence. Immunity to PI was found only when it was presumed that a phonemic representation of the target items existed and that information provided discriminative information. In all other cases, PI was observed. The finding that PI effects correspond with the manipulation of phonemic information in a principled fashion provides strong evidence for the role of phonemic codes in producing short-term PI effects.