Deep dyslexia, imageability, and ease of predication

A development of existing theories of deep dyslexia is outlined. It proposes that the effects of imageability upon the ease of reading of words by deep dyslexics occur as a result of variation in the ease with which individual words summon semantic predicates, on the basis of which reading responses can be made. Ease-of-predication scores are obtained for a corpus of nouns and found to be, as hypothesized, closely related to imageability scores. It is shown that the other major characteristics of deep dyslexia can also be accounted for by this proposed mechanism. These include the well-established effects of syntactic category (in particular, of the distinction between content and function words) upon reading. Further evidence is provided that this effect may be attributed to variation in ease of predication.     

Ease of predication does not account for imageability effects in performance: a reply to Jones (2002)

In this paper we defend our views against claim that the criticism of the ease of predication hypothesis (Jones, 1985) made by de Mornay Davies and Funnell (2000) is "fundamentally flawed." Jones raises five issues concerning the content of the text, the reliability of effects of ease of predication, the generation of predicates, semantic features, and memory retrieval. We address each of these issues in turn and show that either a critical point raised is not made, or the point is mistaken. More importantly we show that our empirical findings, which are entirely overlooked by Jones, unequivocally support the view that ease of predication does not account for imageability effects in performance.     

The Effect of Imageability and Predicability of Cues in Autobiographical Memory

Four experiments investigated the role of imagery in the recollection of autobiographical memories. The first two experiments examined the effects of word imageability and word frequency on the retrieval of personal memories in a cued autobiographical memory task. They showed that the imageability of cues (but not frequency) mediates specificity in the recall of personal memories. Experiment 2 explored how different imagery modalities (visual, olfactory, tactile, auditory, and motor) influence autobiographical retrieval. Consistent with research on imagery modalities in verbal learning paradigms, visual imageability emerged as the most significant predictor of specificity. Experiments 3 and 4 examined how far a knowledge-based account of imagery effects might account for these effects, using predicability as a measure of semantic richness of a cue. Results found that visual imageability of cues accounted for more variance in specificity of recall than did predicability. The results are explained in terms of the way images represent the most efficient form of summarizing the information that can be used at each stage of the recollection process: setting the retrieval plan, strategic search, and evaluation of candidate episodes.     

Semantic representation and ease of predication

Jones' (1985) Ease of Predication hypothesis, which states that underlying differences in the semantic representation of concrete and abstract words can be explained in terms of disproportionate numbers of semantic predicates, is explored in two experiments. The results suggest that (1) the advantage shown by concrete words in terms of greater number of predicates is only apparent for words of low frequency, and (2) Jones' case of predication variable does not accurately reflect predicate distributions, or differences in imageability. Rather, it appears to represent differences in concreteness. As such, the validity of this concept as the basis of theories of semantic representation is questioned. Models based on the assumption of a "richer" semantic representation for concrete words are therefore not supported.     

On Speaking Thus: the Semantics of Indirect Discourse

Indexical predication is possible as well as the more familiar indexical reference. 'My curtains are coloured thus' describes my curtains. The indexical predicate expression it contains ('coloured thus') stands to possible non-indexical replacements ('red') as a referring indexical ('he') does to possible non-indexical replacements ('Tom'), in that it calls upon the context of utterance to fix its semantic contribution to the whole. Indexical predication is the natural resource to call upon in talk about skilful human performances, where we exhibit considerable know-how but little explicit know-that. Speech is among such performances. Both direct and indirect speech reports may be illuminated by seeing them in the light of this thought. A corollary of the approach is that the prospects of providing a formal semantic treatment of indirect speech do not look good.     

Word identification: Imageability, semantics, and the content-functor distinction

It has often been suggested that different special-purpose mechanisms underlie the processing of content words and function words. The received view is that processing differences in various tasks arise because of differences between these word classes in terms of their semantic/syntactic function, despite the fact that these tasks often involve word processing in the absence of any sentence context. It is also well known that the ease with which a word arouses a sensory impression is often a good predictor of word-processing performance, yet the literature largely ignores the fact that, typically, imageability and word class are confounded factors. A series of three experiments shows that in the context of a Stroop task, the typical content-function word difference can be obtained, but that this word class difference disappears completely when the items are matched on the dimension of imageability. It is suggested that the processing of decontextualized content and function words does not necessarily engage distinct special purpose processing mechanisms. Implications for understanding previously published work on word class effects in other paradigms are briefly noted.     

Imageability and semantic association in the representation and processing of event verbs

This study examined the relative salience of imageability (the degree to which a word evokes mental imagery) versus semantic association (the density of semantic network in which a word is embedded) in the representation and processing of four types of event verbs: sensory, cognitive, speech, and motor verbs. ERP responses were recorded, while 34 university students performed on a lexical decision task. Analysis focused primarily on amplitude differences across verb conditions within the N400 time window where activities are considered representing meaning activation. Variation in N400 amplitude across four types of verbs was found significantly associated with the level of imageability, but not the level of semantic association. The findings suggest imageability as a more salient factor relative to semantic association in the processing of these verbs. The role of semantic association and the representation of speech verbs are also discussed.     

Dimensions of metaphor

Two rating studies examined several dimensions of metaphorical sentences. A pool of 260 metaphors was constructed, all in the form “(noun phrase) is/are (noun phrase).” In Study 1 all of the items, and in Study 2, 98 of the items were evaluated on ten scales presumed to be important to the comprehension or interpretation of metaphors: semantic relatedness of the subject and predicate, comprehensibility, imageability, imageability of the subject (topic), imageability of the predicate (vehicle), degree of metaphoricity, metaphor goodness, ease of interpretation, number of alternative interpretations, and felt familiarity of the metaphoric ground. Both experiments revealed the rated dimensions to be highly interrelated, but some analyses allowed evaluation of alternative predictions based on current theoretical approaches to metaphor quality and interpretation. The results indicated consistent but mixed support for the general poisitions under consideration as each appeared to have strong and weak areas of applicability. The interrelationships among the scales are discussed, together with implications of the findings for current theories and future metaphor research.     

Evidence for the activation of sensorimotor information during visual word recognition: the body-object interaction effect

We examined the effects of sensorimotor experience in two visual word recognition tasks. Body-object interaction (BOI) ratings were collected for a large set of words. These ratings assess perceptions of the ease with which a human body can physically interact with a word's referent. A set of high BOI words (e.g., mask) and a set of low BOI words (e.g., ship) were created, matched on imageability and concreteness. Facilitatory BOI effects were observed in lexical decision and phonological lexical decision tasks: responses were faster for high BOI words than for low BOI words. We discuss how our findings may be accounted for by (a) semantic feedback within the visual word recognition system, and (b) an embodied view of cognition (e.g., Barsalou's perceptual symbol systems theory), which proposes that semantic knowledge is grounded in sensorimotor interactions with the environment.     

Noun Imageability Facilitates the Acquisition of Plurals: Survival Analysis of Plural Emergence in Children

Some research in child language suggests that semantically general verbs appear in grammatical structures earlier than semantically complex, specific ones. The present study examines whether this was the case in nouns, using imageability as a proxy measure of semantic generality. Longitudinal corpus data from 12 children from the Manchester corpus in CHILDES were used to obtain information on the first occurrence of plurals. A total of 3,560 uninflected nouns were identified in the corpora, of which 1,202 were observed in the plural. Survival analyses indicated that the chance of observing a plural form increases with the imageability rating of the noun, even after accounting for the age of acquisition of the uninflected noun, maternal input frequency, and word length. Noun imageability thus facilitates the acquisition of plural forms. This finding contradicts the observations from verbs, and indicates that the acquisition of grammar is facilitated by high imageability rather than semantic generality.     

Word imageability effects on naming: a pilot investigation of beginning readers of Turkish

Word imageability, a semantic variable, in naming by beginning readers of English is well documented particularly with poor readers naming high imageable words more accurately than low imageable words. The present study examined the role of imageability on word naming by 20 good and 20 poor beginning readers as a function of orthographic transparency by utilizing the peculiarities of the transparent Turkish writing system. Neither good nor poor beginning readers show any evidence of imageability for Turkish suggesting that the contribution of imageability to word naming may indeed be determined by orthographic transparency. Implications of these findings are discussed.     

What's in a word? A parametric study of semantic influences on visual word recognition

To what extent does semantic information play a functional role in visual word recognition? Theories of word recognition vary in the importance assigned to semantic information in visual lexical decision, with past research suggesting that the nature of the foils is a crucial determinant of semantic reliance. Here, we explored the conditions under which semantic variables influence lexical decision. Normal readers performed visual lexical decision tasks in which imageability and semantic priming were manipulated, with nonword foils varying systematically in their orthographic and phonological similarity to the real words. The effects of imageability and semantic priming increased in magnitude as nonword foils became progressively more wordlike. These findings provide a clear illustration of the flexible use of semantic information to support normal visual word recognition.     

Semantic effects in word naming: Evidence from English and Japanese Kanji

Three experiments investigated whether reading aloud is affected by a semantic variable, imageability. The first two experiments used English, and the third experiment used Japanese Kanji as a way of testing the generality of the findings across orthographies. The results replicated the earlier findings that readers were slower and more error prone in reading low-frequency exception words when they were low in imageability than when they were high in imageability (Strain, Patterson, & Seidenberg, 1995). This result held for both English and Kanji even when age of acquisition was taken into account as a possible confounding variable, and the imageability effect was stronger in Kanji compared to English.     

Effects of association and imageability on phonological mapping

In two experiments, we examined the influence of semantic activation on the generation of a phonological code, testing the interactivity assumption common to both dual-route and interactive-activation models. In Experiment 1, subjects named regular and irregular targets preceded by related and unrelated primes. In Experiment 2, these variables and target imageability were manipulated. Both relatedness and imageability interacted with regularity, indicating that semantic activity speeds access to a phonological code.     

Neuroanatomically separable effects of imageability and grammatical class during single-word comprehension

The present study characterizes the neural correlates of noun and verb imageability and addresses the question of whether components of the neural network supporting word recognition can be separately modified by variations in grammatical class and imageability. We examined the effect of imageability on BOLD signal during single-word comprehension of nouns and verbs. Subjects made semantic similarity judgments while undergoing functional magnetic resonance imaging (fMRI). Nouns and verbs were matched on imageability, and imageability varied continuously within a grammatical category. We observed three anatomically separable effects: a main effect of grammatical class, a main effect of imageability, and an imageability by grammatical class cross-over interaction. The left superior parietal lobule and a region in the left fusiform responded similarly to increases in noun and verb imageability; the left superior temporal gyrus showed greater activity for verbs than nouns after imageability was matched across grammatical class; and, in both the left middle temporal gyrus and the left inferior frontal lobe, a decrease in noun but not verb imageability resulted in higher BOLD signal. The presence of reliable and anatomically separable main effects of both imageability and grammatical class renders unlikely the hypothesis that previously reported dissociations between nouns and verbs can be dismissed as imageability effects. However, some regions previously thought to respond to grammatical class or imageability instead respond to the interaction of these variables.     

Imageability and ambiguity effects in speeded naming: convergence and divergence

A current area of controversy within the literature on visual word recognition concerns the extent to which semantic information influences the computation of phonology. Experiment 1 revealed that both the imageability effect and the ambiguity advantage seen in the speeded naming task are confined to words with atypical mappings between spelling and sound. Nonetheless, it is possible that either of these effects may arise from the operation of the direct rather than the semantic pathway. Experiment 2 therefore included nonword fillers in order to minimize semantic reliance during speeded naming. This manipulation removed the imageability effect, indicating a semantic locus, but the ambiguity advantage remained, suggesting a nonsemantic locus. These results are considered in the context of computational models that incorporate a semantic level of representation.     

When does a deep dyslexic make a semantic error? The roles of age-of-acquisition, concreteness, and frequency

Semantic reading errors are the central and defining feature of deep dyslexia. This study compared the words the deep dyslexic patient LW read correctly with those she omitted and those to which she produced semantic errors in terms of their concreteness, age-of-acquisition, frequency, and length. Semantic errors were made to less concrete, later-acquired, and shorter words than were read correctly; there was no reliable effect of word frequency. More importantly, the actual semantic errors produced were later-acquired than the stimulus words, but they were not more concrete or reliably more frequent. These results implicate age-of-acquisition in the process that produces semantic errors. It is proposed that concreteness determines the specificity of the semantic system to activate a set of candidate responses and that age-of-acquisition biases the ease with which certain words can be selected from this set to be produced as reading responses.     

Cognitive aspects of lexical availability

Lexical availability measures the ease with which a word can be generated as a member of a given category. It has been developed by linguistic studies aimed, among other things, at devising a rational basis for selecting words for inclusion in dictionaries. The measure accounts for the number of people who generated a given word as a member of a designated semantic category and the position in which they produce the word. We present an analysis of lexical availability from a cognitive perspective. Data were analysed for Spanish speakers generating words from five semantic categories—clothes, furniture, body parts, animals, and intelligence. Six properties of words were investigated as potential predictors of lexical availability. Predictors were concept familiarity, typicality, imageability, age of acquisition, word frequency, and word length. Categories differed on these variables, and regression analysis found concept familiarity, typicality, and age of acquisition to be significant predictors of lexical availability. The cognitive basis of these findings and the practical consequences of selecting words on the basis of lexical availability are considered.     

Imageability and distributional typicality measures of nouns and verbs in contemporary English

Dissociations between noun and verb processing are not uncommon after brain injury; yet, precise psycholinguistic comparisons of nouns and verbs are hampered by the underrepresentation of verbs in published semantic word norms and by the absence of contemporary estimates for part-of-speech usage. We report herein imageability ratings and rating response times (RTs) for 1,197 words previously categorized as pure nouns, pure verbs, or words of balanced noun-verb usage on the basis of the Francis and Ku?era (1982) norms. Nouns and verbs differed in rated imageability, and there was a stronger correspondence between imageability rating and RT for nouns than for verbs. For all word types, the image-rating-RT function implied that subjects employed an image generation process to assign ratings. We also report a new measure of noun-verbtypicality that used the Hyperspace Analog to Language (HAL; Lund & Burgess, 1996) context vectors (derived from a large sample of Usenet text) to compute the mean context distance between each word and all of thepure nouns andpure verbs. For a subset of the items, the resulting HAL noun-verb difference score was compared with part-of-speech usage in a representative sample of the Usenet corpus. It is concluded that this score can be used to estimate the extent to which a given word occurs in typical noun or verb sentence contexts in informal contemporary English discourse. The item statistics given in Appendix B will enable experimenters to select representative examples of nouns and verbs or to compare typical with atypical nouns (or verbs), while holding constant or covarying rated imageability.