Masked priming is abstract in the left and right visual fields

Two experiments assessed masked priming for words presented to the left and right visual fields in a lexical decision task. In both Experiments, the same magnitude and pattern of priming was obtained for visually similar (kiss-KISS) and dissimilar (read-READ) prime–target pairs. These findings provide no support for the hypothesis that word identification is mediated by separate and lateralized abstract and specific visual form systems. Strikingly, equivalent priming was observed when primes and targets were presented to the same or opposite visual fields, suggesting that priming occurs after visual information from the two hemispheres is integrated.     

Masked priming is abstract in the left and right visual fields

Two experiments assessed masked priming for words presented to the left and right visual fields in a lexical decision task. In both Experiments, the same magnitude and pattern of priming was obtained for visually similar (kiss-KISS) and dissimilar (read-READ) prime-target pairs. These findings provide no support for the hypothesis that word identification is mediated by separate and lateralized abstract and specific visual form systems. Strikingly, equivalent priming was observed when primes and targets were presented to the same or opposite visual fields, suggesting that priming occurs after visual information from the two hemispheres is integrated.     

Different methods of lexical access for words presented in the left and right visual hemifields

Right-handed adults were asked to identify by name bilaterally presented words and pronounceable nonwords. For words in the normal horizontal format, word length (number of letters) affected left visual hemifield (LVF) but not right visual hemifield (RVF) performance in Experiments 1, 2, 3, 5, and 6. This finding was made for words of high and low frequency (Experiment 6) and imageability (Experiment 5). It also held across markedly different levels of overall performance (Experiments 1 and 2), and across different relative positionings of short and long words in the LVF and RVF (Experiment 3). Experiment 4 demonstrated that the variable affecting LVF performance is the number of letters in a word, not its phonological length. For pronounceable nonwords (Experiment 7) and words in unusual formats (Experiment 8), however, length affected both LVF and RVF performance. The characteristics identified for RVF performance in these experiments also hold for the normal reading system. In this (normal) system the absence of length effects for horizontally formatted words is generally taken to reflect the processes involved in lexical access. Length effects in the normal reading system are thought to arise when lexical access for unusually formatted words and for the pronunciation of nonwords requires the short-term storage of information at a graphemic level of analysis. The characteristics of LVF performance indicate that horizontally formatted words presented to the right cerebral hemisphere can only achieve lexical access by a method that requires the short-term storage of graphemic information. This qualitative difference in methods of lexical access applies regardless of whether the right hemisphere is seen as accessing words in the left hemisphere's lexicon or words in a lexicon of its own.     

Semantic priming effects for stimuli presented to the right and left visual fields

Studies that have addressed the possibility of hemispheric differences in semantic priming effects have yielded contradictory results. This paper reports the findings of two experiments intended to shed greater light on the issue of hemispheric differences in semantic priming. Experiment 1 used a hemiretinal paradigm and examined manual response latency and response accuracy to four types of word pairs; categorically related, syntactically related, unrelated, and pairs containing a nonword member. Experiment 2 examined the effects of unrecognized, disambiguating flank words on verbal responses to a centrally presented homograph. Experiment 1 yielded no significant visual field differences in magnitude of priming effects when response latency served as the dependent measure, although categorical relatedness facilitated response accuracy for left but not right visual field stimuli. In experiment 2, the disambiguating words had a significant effect on meaning interpretation of the homographs that was independent of visual field of presentation. Taken together, the results of these studies are interpreted as indicating that semantic aspects of linguistic input are automatically processed and can influence the content and latency of subsequent responses, whether presented to the left or right visual field.     

Oral report of words and word approximations presented to the left or right visual field

Subjects reported letter strings forming words, pronounceable high approximations to words, and unpronounceable low approximations to words presented tachistoscopically to the left or right visual field (LVF, RVF). (a) For number of strings totally correct, the same RVF superiority was obtained with high approximations as with words, the field difference with low approximations being negligible. (b) In contrast, for letter scores from partially correct strings, RVF superiority did not vary with string type. Finding (a) is interpreted to indicate that the left hemisphere is differentially specialized for processing words as units and that requiring oral report makes pronounceable strings processable as word-like units. Finding (b) suggests that the left hemisphere is not specialized for processing subword fragments.     

Stroop interference in the left and right visual fields

The Stroop Color-Word test was employed to study the amount of interference in naming colors when stimuli were presented in either visual field. It was hypothesized that more Stroop interference would occur in the dominant hemisphere. The subjects were 24 right-handed college students, between 18 and 25 years old. There were three conditions in each visual field: Interference, Reading, and Naming. Each slide was presented for 150 msec preceded by a fixation dot. Subjects were asked to verbally report as fast and as accurately as they could either the color words or the color names, depending upon the conditions. Reaction times and error rates were analyzed. As expected, significantly higher error rates were obtained when color words were presented in the right visual field under the Stroop interference condition. Under this same condition, reaction time analysis yielded no significant differences between hemispheres.     

Perceived frequency of concrete and abstract words

Studies are reported which show that concrete and abstract words of equal objective frequency (based on available , word counts) are not perceived as being equal. The abstract word has greater perceived frequency than the concrete word. The judged variety of contexts in which a word appears correlates very highly with perceived frequency. The results have relevance to the design of learning studies in which concrete and abstract words are used. and also to the interpretation of such experiments.     

Development of differences in response latencies to right and left visual fields

Robust lateralization developed in right-handed adults who were asked to judge letter pairs as "same" or "different" during 4608 trials. By the end of the first two blocks (768 trials) "same" responses were favored when presented in the RVF (transmitted directly to the left hemisphere) and "different" responses were favored when presented in the LVF (transmitted direction to the right hemisphere). This gradually reversed over sessions with "same" responses becoming faster for letters presented in the LVF, and "different" responses becoming faster for stimuli presented in the RVF. The laterality acquired under these conditions was cumulative and reproducible, appeared in all 16 subjects, and was preserved between sessions a week apart. The data suggest that laterality is a flexible and reversible characteristic of the human brain even when stimulus and task remain constant.     

Memory for concrete and abstract words in bilingual speakers

The dual-code hypothesis of Paivio was taken to imply that bilingual speakers should show poorer memory for the language in which concrete words appeared than the language in which abstract words appeared. The results of two experiments with German-English bilinguals, one using a recognition memory procedure and the other using the free recall task, found the opposite state of affairs. Semantic recognition, free recall, and memory for language of occurrence were all found to be superior for concrete words. Two hypotheses were advanced. One, called the "cultural imagery hypothesis," assumes that images may be culture specific, while the other hypothesis interprets the outcome in terms of the relations between stored attributes. An analysis of the experiment as an attribute-memory procedure is presented.     

Different modes of word recognition in the left and right visual fields

We confirm previous evidence indicating that word length has a substantial effect on word recognition in the LVF but a much weaker effect in both the RVF and fovea. The nature of encoding in the LVF is not altered when the words are vertically displayed (Experiment 2), and the effect cannot therefore be entirely due to scanning artefact or acuity gradients in peripheral vision. We provide evidence that links the asymmetrical influence of word length directly to hemispheric specialization: left-handers, who as a group are much less consistently lateralized than right-handers are also less affected by word length in the LVF on the average (Experiment 3). This occurs because the asymmetry for certain left-handers is either very weak or, in some cases, is the complete reverse of the asymmetry observed in right-handers. Finally, we demonstrate that the length x field interaction is observed in lexical decisions (Experiment 4) which do not entail pronunciation of written words. There is some indication that concrete, high-imageable words produce a smaller effect of length in the LVF than abstract, low-imageable words, and we discuss this outcome in relation to the proposal that the right hemisphere can sometimes extract a lexical code from letter information. The concept of distinct modes of word recognition in the LVF and RVF clarifies a number of issues in laterality research, and suggests a new approach to evaluating group differences in half-field performance.     

Perception of geometrical arrays tachistoscopically exposed in right and left visual fields.

Geometrical stimuli (48 6-item arrays of familiar forms, e.g., circle), tachistoscopically presented in the right or left visual field, were more accurately perceived in the right than left visual field by 15 college students. Targets about half the length of the displays exposed here were perceived with equal facility in both visual fields (Bryden, 1960). Results suggest that length of array might affect the difference in perceptual accuracy of forms shown in the right and left visual fields. Figures in the right visual field were predominantly processed from left to right, and forms in the left visual field from right to left. Since more symbols were identified in the right than left visual field, the left to right encoding sequence may be more efficient than a right to left movement. Limited experience of most Ss in reading symbols from left to right is probably only one factor. Extensive experience reading alphabetical material from left to right might have developed the physiological mechanism underpinning this sequence more than the one serving the opposite movement.     

Asymmetries for the categorization of kanji nouns, adjectives, and verbs presented to the left and right visual fields

Kanji is one form of written Japanese in which the symbolic/analytic characteristics of language are dissociated from systematic phonetic characteristics; as such, it makes possible a more careful test of which aspect of language is responsible for the frequently observed superior left-hemisphere performance. In this study, subjects were asked to categorize tachistoscopically presented kanji as nouns, adjectives, or verbs. The previously reported (Hatta 1977, Neuropsychologia, 15, 685–688) left-visual-field advantage for kanji was found only in the case of nouns. Adjectives and verbs were processed more rapidly and correctly in the right visual field.     

Context availability and the recall of abstract and concrete words

Predictions of an automatic-imagery, strategic-imagery, and context-availability hypothesis of concreteness effects in free recall were examined. In each experiment, recall of abstract and concrete words controlled for rated context availability was compared with the typical situation in which context availability is confounded with imageability. In Experiment 1, a directed intentional-recall task produced concreteness effects in recall. Experiment 2 compared concreteness effects in recall following three orienting tasks: imagery rating, context-availability rating, and a directed intentional-memory task. Concreteness effects in the context-availability-controlled condition were found following the imagery-rating and the directed intentional-memory tasks, but not after the context-availability-rating task. In Experiment 3, subjects reported the strategies that they used to encode the list. Subjects reporting an imagery strategy showed concreteness effects for words controlled for rated context availability, but those not reporting it did not. These results support a strategic-imagery view of concreteness effects in free recall.     

Concreteness effects revisited: The influence of dynamic visual noise on memory for concrete and abstract words

Two experiments are presented that investigate the effects of dynamic visual noise (DVN) on memory for concrete and abstract words. Memory for concrete words is typically superior to that of abstract words and is referred to as the concreteness effect. DVN is a procedure that has been demonstrated to interfere selectively with visual working memory and the generation of images from long-term memory. It was reasoned that if concreteness effects arise because of the ability of the latter to activate visual representations, then DVN should selectively impair memory for concrete words. Experiment 1 found DVN to selectively reduce free recall of concrete words. Experiment 2 investigated recognition memory and found DVN to reduce memory accuracy and remember responses, while increasing know responses to concrete words.     

Free recall of concrete and abstract words in poor and normal readers

The present study compared poor and normal readers in second and sixth grade on free recall of concrete and abstract words. On the basis of the assumption that memory for abstract words relies more heavily upon linguistic coding ability than does memory for concrete words, it was expected that poor readers would have much greater difficulty on recall of abstract words than would normal readers, but would more closely approximate the normal readers on recall of concrete words. The hypothesis was confirmed at the second-grade level but not at the sixth-grade level, wherein the magnitude of group differences on concrete words was comparable to that on abstract words. Post hoc analyses of intrusion errors suggested that the linguistic coding hypothesis may be a viable explanation of reader group differences on memory tasks only at lower age levels.