A Web-based interface to calculate phonotactic probability for words and nonwords in English

Phonotactic probability refers to the frequency with which phonological segments and sequences of phonological segments occur in words in a given language. We describe one method of estimating phonotactic probabilities based on words in American English. These estimates of phonotactic probability have been used in a number of previous studies and are now being made available to other researchers via a Web-based interface. Instructions for using the interface, as well as details regarding how the measures were derived, are provided in the present article. The Phonotactic Probability Calculator can be accessed athttp://www.people.ku.edu/~mvitevit/PhonoProbHome.html.     

Rhyme decisions to spoken words and nonwords

Lexical effects in auditory rhyme-decision performance were examined in three experiments. Experiment 1 showed reliable lexical involvement: rhyme-monitoring responses to words were faster than rhyme-monitoring responses to nonwords; and decisions were faster in response to high-frequency as opposed to low-frequency words. Experiments 2 and 3 tested for lexical influences in the rejection of three types of nonrhyming item: words, nonwords with rhyming lexical neighbors (e.g.,jop after the cuerob), and nonwords with no rhyming lexical neighbor (e.g.,vop afterrob). Words were rejected more rapidly than nonwords, and there were reliable differences in the speed and accuracy of rejection of the two types of nonword. The advantage for words over nonwords was replicated for positive rhyme decisions. However, there were no differences in the speed of acceptance, as rhymes, of the two types of nonword. The implications of these results for interactive and autonomous models of spoken word recognition are discussed. It is concluded that the differences in rejection of nonrhyming nonwords are due to the operation of a guessing strategy.     

Early effects of neighborhood density and phonotactic probability of spoken words on event-related potentials

All current models of spoken word recognition propose that sound-based representations of spoken words compete with, or inhibit, one another during recognition. In addition, certain models propose that higher probability sublexical units facilitate recognition under certain circumstances. Two experiments were conducted examining ERPs to spoken words and nonwords simultaneously varying in phonotactic probability and neighborhood density. Results showed that the amplitude of the P2 potential was greater for high probability-density words and nonwords, suggesting an early inhibitory effect of neighborhood density. In order to closely examine the role of phonotactic probability, effects of initial phoneme frequency were also examined. The latency of the P2 potential was shorter for words with high initial-consonant probability, suggesting a facilitative effect of phonotactic probability. The current results are consistent with findings from previous studies using reaction time and eye-tracking paradigms and provide new insights into the time-course of lexical and sublexical activation and competition.     

Preliminary letter identification in the perception of words and nonwords.

Words with mixed uppercase and lowercase letters (e.g. fAdE) were perceived more accurately than mixed-case pseudowords (e.g. gAdE), and mixed-case pseudowords were perceived more accurately than mixed-case unrelated letter strings (e.g. eFdT). In addition, same-case words were perceived more accurately than their mixed-case counterparts. The same held true for pseudowords but not for unrelated letter strings. The results are compatible with the view that both letter identify and visual form information are used in word perception.     

Visual search through words and nonwords in horizontal and vertical orientations.

In a repeated measurement design, 18 college women searched for target letters in 18 lists of common words, rare words, and nonwords arranged either vertically or horizontally. The mean search time in seconds for three trials in each of six conditions was expected to be significantly slower for nonwords than for words and for vertical orientations than for horizontal orientations. More importantly, a significant interaction was predicted between direction of search and the type of list searched. Results confirmed earlier findings that the two main effects were significant; the significant interaction provided empirical evidence that consideration needs to be given to both intraword redundancy and direction of visual search.     

Isolating visual units in the perception of words and nonwords

In three experiments, reaction times for same-different judgments were obtained for pairs of words, pronounceable nonwords (pseudowords), and unpronounceable nonwords. The stimulus strings were printed either in a single letter case or in one of several mixtures of upper- and lowercase letters. In Experiment 1, the stimuli were common one- and two-syllable words; in Experiment 2, the stimuli included both words and pseudowords; and in Experiment 3, words, pseudowords, and nonwords were used. The functional visual units for each string type were inferred from the effects that the number and placement of letter case transitions had onsame reaction time judgments. The evidence indicated a preference to encode strings in terms of multiletter perceptual units if they are present in the string. The data .also suggested that whole words can be used as functional visual units, although the extent of their use depends on contextual parameters such as knowledge that a word will be presented.     

Reading, spelling, and recognition of briefly exposed words and nonwords.

Four groups distinct in terms of English reading comprehension and spelling skills were identified among 141 Japanese college students: 5 good readers and spellers, 6 good readers but poor spellers, 3 poor readers but good spellers, and 4 poor readers and poor spellers. They were then tested on instantaneous recognition of words and nonwords. Analysis showed that the recognition performance was more strongly associated with spelling than with reading comprehension. Immediate memory and "sophisticated" guessing, which were associated with spelling, were considered to be critical for the recognition task, but the hypothesis that a common processing mechanism is involved in instantaneous word recognition and spelling was rejected.     

Judgments of duration, figure-ground contrast, and size for words and nonwords

Does the word-superiority effect on letter discrimination result in a word-superiority effect on duration judgments? We examined this question in five experiments. In the first four experiments, we have demonstrated that (1) words shown for 32-80 msec were judged as presented longer than non-words shown for the same duration; (2) this word-superiority effect persists if the stimuli are shown for an objective duration of up to 250 msec; and (3) these effects can be extended to judgments of figure-ground contrast and letter size. These findings extend existing data on effects of processing fluency on perceptual judgments. In Experiment 5, we found that duration judgments were higher for words than for pronounceable nonwords, and duration judgments were higher for pronounceable non-words than for nonpronounceable nonwords. We discuss the implications of this finding for the discrepancy-attribution hypothesis.     

An online calculator to compute phonotactic probability and neighborhood density on the basis of child corpora of spoken American English

An online calculator was developed (www.bncdnet.ku.edu/cml/info_ccc.vi) to compute phonotactic probability—the likelihood of occurrence of a sound sequence—and neighborhood density—the number of phonologically similar words—on the basis of child corpora of American English (Kolson, 1960; Moe, Hopkins, & Rush, 1982) and to compare its results to those of an adult calculator. Phonotactic probability and neighborhood density were computed for a set of 380 nouns (Fenson et al., 1993) using both the child and adult corpora. The child and adult raw values were significantly correlated. However, significant differences were detected. Specifically, child phonotactic probability was higher than adult phonotactic probability, especially for highprobability words, and child neighborhood density was lower than adult neighborhood density, especially for words with high-density neighborhoods. These differences were reduced or eliminated when relative measures (i.e., z scores) were used. Suggestions are offered regarding which values to use in future research.     

Stroop-like serial position effects in color naming of words and nonwords

Color-naming latencies to noncolor words and nonwords were faster when the onset or final phoneme of the displays corresponded to the onset or final phoneme of the color response. For example, for displays printed in red, the word rack and nonword rask, which share the initial onset phoneme with the response, led to faster naming than did the control word chap and nonword chup. Conversely, when the onset or final phoneme of the displays matched the onset or final phoneme of a conflicting color response (e.g., rack printed in blue), latencies were longer than to control items. Facilitation effects were stronger than interference effects, and the onset phoneme facilitation effect was augmented by coloring only the initial letter in the display. It is hypothesized that nonlexical processes that govern the translation of print to speech may be a source of facilitation in Stroop-like tasks, whereas lexical processes are more likely to contribute to interference.     

The role of familiar units in perception of words and nonwords

This paper investigates the effects of familiarity with whole-word units and letter-cluster units in perceptual encoding of letter strings. Subjects viewed brief, masked presentations of words and pronounceable pseudowords differing in letter cluster frequency. Identification of both display types was compared to control single letters. Perceptual accuracy was indexed by probe forced-choice responses and full verbal reports of the displays. Evidence that familiarity of whole-word units facilitated encoding was mixed but, on balance, favorable. Evidence that familiarity of letter-cluster units facilitated encoding was completely absent. This negative finding is surprising in view of the fact that we did obtain a large advantage of letters in pseudo-words as well as words over single letters. The discussion section considers an alternative to the view that perceivers use detectors for familiar letter-cluster units in the process of forming representations of pronounceable, orthographically regular letter strings.     

A re-evaluation of the phonological similarity effect in adults' short-term memory of words and nonwords

The phonological similarity effect (PSE) was studied in two tasks of serial recall, in one task of serial recognition and one item identification task. PSE occurred only in the former three tasks involving memory of order when study items were words and nonwords with an associative connectedness to long-term memory. Nonwords that, according to a reaction time assessment of associative value, were less well connected to long-term memory mechanisms, were not sensitive to phonological similarity. These results are discussed in relation to contemporary models of short-term memory that explain the PSE as a result of confusions of items that are similarly encoded in a phonological layer. This layer is identified as a higher-level phonological space that is accessed by words and nonwords of high associative value and not by nonwords of low associative value.     

The role of bigram frequency in the perception of words and nonwords

Memory & Cognition - Adult subjects decided whether strings of four, five, or six letters formed words or nonwords. Words and nonwords were equally probable stimuli, and there were equal...     

Detection of letter repetition in words and nonwords: the effect of opposite-case distractors.

This study tested whether it is the repetition of the letter's name and not its shape that is detected faster in a word than in a nonword (Krueger, 1989). Ss judged whether the same letter shape or the same letter name was repeated in a 6-letter word or nonword. When the shape was repeated, the word advantage was nearly as large (about 50 ms) when Ss looked for a physical match as when they looked for a name match. When the 2 repeated letters differed in case, however, the word advantage was very large (208 ms) when Ss looked for a name match and were thus rewarded for nonvisual coding, but the advantage vanished ((-35)-ms word deficit) when Ss looked for a physical match and were thus penalized for nonvisual coding. This indicates that letter names are much more accessible in words than in nonwords, and that words are primarily encoded nonvisually.     

On the processes underlying stimulus-familiarity effects in recognition of words and nonwords

The authors investigated the recognizability of recently studied word and nonword stimuli in relation to both experimentally controlled prior frequency of occurrence and, for words, normative frequency (assessed by counts of occurrences in printed English). The interaction between these variables was small and nonsignificant across all conditions of 2 experiments. Patterns of recognition measures in relation to controlled prior frequency, but not normative frequency, appeared interpretable in terms of response biases generated by long-term priming. Application of a global memory model and analyses of correlations among item categories yielded evidence for a lexicality dimension underlying normative-frequency effects and an implication that "word-frequency effects" on recognition are better termed lexicality effects.     

Semantics and semantic errors: implicit access to semantic information from words and nonwords in deep dyslexia

In this paper we describe dissociations of implicit versus explicit access to semantic information in a patient with deep dyslexia. This acquired reading disorder is characterized by the production of morphological (e.g., SLEEP read as SLEEPING) and semantic errors (e.g., HEART read as BLOOD) and consequently provides a potential window into the operation of both aspects of the language system. The deep dyslexic patient in this study (JO) demonstrated implicit semantic access to items in a number of tasks despite the fact that she was unable to correctly read these items aloud. The findings from this study are consistent with a model of lexical deficits that distinguishes between explicit and implicit access to lexical representations on the basis of inhibitory processes.     

The effect of phonemic processing on the retention of graphemic representations for words and nonwords

The three experiments reported in this study were each conducted in two phases. The first phase of Experiment 1 involved a same-different comparison task requiring “same” responses for both mixed-case (e.g., MAIN main) and pure-case (e.g., near near) pairs. This was followed by Phase 2, a surprise recognition test in which a graphemic effect on word retention was indicated by the superior recognition accuracy obtained for pure-case compared with mixed-case pairs. The first phases of Experiments 2 and 3 involved pronounceability and imageability judgment tasks, respectively. Graphemic retention was assessed by contrasting recognition accuracy for letter strings presented, during Phase 2, in their original Phase 1 case, with letter strings presented, during Phase 2, in. a graphemically dissimilar new case. The experiments provided evidence that there was minimal retention of the graphemic representations from which the phonemic representations of words are generated and, further, that the locus of this effect is probably postlexical. Nonwords were recognized more accurately than words in all three experiments. The latter result was attributed to differences between nonwords and words in both graphemic retention and semantic distinctiveness.     

Repetition effects for words and nonwords as indexed by event-related fMRI: a preliminary study

We have previously shown differential effects of stimulus familiarity on the repetition-related responses in right fusiform cortex to both faces and symbols. Repetition of familiar stimuli produced a response decrease, whereas repetition of unfamiliar stimuli produced a response increase. In the present experiment, we used words and nonwords as the familiar and unfamiliar stimuli respectively. In this case, the only fusiform region showing the familiarity-by-repetition interaction was in anterior left fusiform. This left-lateralisation of the fusiform interaction is consistent with our hypothesis that these repetition-related effects occur in the same regions responsible for perceptual recognition of familiar stimuli.     

The phonology-morphosyntax interface: affixed words in agrammatism.

In three experiments with nondysarthric agrammatics, we explored the association between phonology and morphosyntax. (1) Contrasting phonological and nonphonological factors on inflectional-affix production of English verbs across three tasks in eight agrammatics, longer stem-syllabic length and stem-final-CC status resulted in poorer affix-production. (2) Studying verb inflections in six agrammatic Spanish-speakers, affix-length and affix-stress correlated with poorer repetition, as did low affix frequency. (3) Four English-speaking agrammatics read aloud and repeated derived words varying in syllable-length and stem-stress reassignment; both contributed independently to word-production difficulty. Phonological complexity of affixes and stems appears to reduce resources for morphological processing in nondysarthric agrammatics.