Biomedical subjects

C Chiarello

Publications and source records attributed to C Chiarello.

17 recordsLinked to original sources

PubMed1992

Another look at categorical priming in the cerebral hemispheres.

This study investigated the effect of exemplar dominance on semantic priming in the left and right visual fields for words that are members of the same category, but not strongly associated. A low proportion of related primes was employed in lexical decision and word pronunciation tasks to assess the automatic activation of word meanings in each cerebral hemisphere. Priming was reliably obtained only in the LVF/right hemisphere. In addition, this effect did not vary with category dominance of the prime:equivalent LVF priming was observed for ROBIN-CROW (high dominant) and DUCK-CROW (low dominant) pairs. These findings support the view that a broader range of related meanings is activated during word recognition in the right, than in the left, hemisphere.

Adult↗

PubMed1992

Semantic additivity and semantic inhibition: dissociable processes in the cerebral hemispheres?

We report the results of two visual half-field semantic priming experiments using a high proportion of related trials to examine hemisphere asymmetries for semantic processes beyond those attributable to automatic meaning activation. Contrary to previous investigations, we obtained inhibition for unrelated trials in both visual fields. However, priming was additive (being greater for words related via category membership and association than for either single dimension) only when words were presented to the RVF/left hemisphere. A third experiment, using centrally presented stimuli, implied that semantic additivity should be attributed to post-access meaning comparisons and inhibition to the generation of semantic expectancies. These results suggest (1) that inhibition and additivity are potentially dissociable "controlled" semantic processes and (2) that the left hemisphere predominates for meaning integration across successively presented words. The availability of finely tuned meaning integration processes in the left hemisphere may contribute to its superiority in language processing, despite right hemisphere competence for some semantic operations.

Adult↗

PubMed1990

Typicality effects in artificial categories: is there a hemisphere difference?

In category classification tasks, typicality effects are usually found: accuracy and reaction time depend upon distance from a prototype. In this study, subjects learned either verbal or nonverbal dot pattern categories, followed by a lateralized classification task. Comparable typicality effects were found in both reaction time and accuracy across visual fields for both verbal and nonverbal categories. Both hemispheres appeared to use a similarity-to-prototype matching strategy in classification. This indicates that merely having a verbal label does not differentiate classification in the two hemispheres.

Adult↗

PubMed1990

Semantic and associative priming in the cerebral hemispheres: some words do, some words don't ... sometimes, some places.

This study investigated spreading activation for words presented to the left and right hemispheres using an automatic semantic priming paradigm. Three types of semantic relations were used: similar-only (Deer-Pony), associated-only (Bee-Honey), and similar + associated (Doctor-Nurse). Priming of lexical decisions was symmetrical over visual fields for all semantic relations when prime words were centrally presented. However, when primes and targets were lateralized to the same visual field, similar-only priming was greater in the LVF than in the RVF, no priming was obtained for associated-only words, and priming was equivalent over visual fields for similar + associated words. Similar results were found using a naming task. These findings suggest that it is important to lateralize both prime and target information to assess hemisphere-specific spreading activation processes. Further, while spreading activation occurs in either hemisphere for the most highly related words (those related by category membership and association), our findings suggest that automatic access to semantic category relatedness occurs primarily in the right cerebral hemisphere. These results imply a unique role for the right hemisphere in the processing of word meanings. We relate our results to our previous proposal (Burgess & Simpson, 1988a; Chiarello, 1988c) that there is rapid selection of one meaning and suppression of other candidates in the left hemisphere, while activation spreads more diffusely in the right hemisphere. We also outline a new proposal that activation spreads in a different manner for associated words than for words related by semantic similarity.

Adult↗

PubMed1989

Visual cerebral lateralization over phases of the menstrual cycle: a preliminary investigation.

This study investigated whether visual cerebral asymmetries would change in phase with hormonal variations during the menstrual cycle. Lexical decision and line orientation tasks were administered during follicular, luteal, and menstrual phases of each woman's cycle. These tasks were also administered to a reference group of male subjects. Signal detection analyses indicated an unvarying RVF advantage in word/nonword discriminability (d') throughout the menstrual cycle, but a phase-dependent shift in left hemisphere response criterion (log beta). Gender differences were present for discriminability of line orientation, and female performance on this task varied over the cycle. The results imply that the neural systems subserving some cognitive functions are sensitive to fluctuations in gonadal steroids and suggest a hormonal basis for gender differences in some visual-spatial functions.

Adolescent↗

PubMed1988

Lexical decision and naming asymmetries: influence of response selection and response bias.

Signal detection measures were used to evaluate the effects of several response variables (manual vs. vocal, Go-NoGo vs. Yes-No) on lexical decision asymmetries. An unvarying right visual field advantage in discriminability (d') was observed in each condition. However, response criteria (beta) varied over visual fields and conditions. Naming and lexical decision were shown to have equivalent asymmetries when the effects of response bias are removed. The results indicate that postaccess decision processes make important contributions to lexical decision asymmetries.

Adult↗

PubMed1988

More on words, hemifields, and hemispheres: a reply to Schwartz and Kirsner.

This paper critically examines the theoretical and empirical basis for two claims made by Schwartz and Kirsner (1986, Brain and Cognition, 5, 354-361): (1) that acuity gradients can account for most visual field effects/interactions reported for horizontally presented words, and (2) the acuity gradients should be considered the "default" explanation for such findings. It is argued here that the acuity gradient account of higher order laterality effects is based on a questionable theory of lexical access, has no empirical support, and cannot explain, even in principle, many lateralization results. It is concluded that acuity gradients make little or no contribution to laterality effects when the stimuli consist of short monomorphemic words, and that theoretical explanations for such effects ought not be accepted by default.

Form Perception↗

PubMed1988

Lateral eyes or lateralized? Hemiretinal and ocular dominance effects on visual field asymmetries for the lexical decision task.

The effects of hemiretinal stimulation and ocular dominance on a visual half-field lexical decision task were investigated. Twelve right-eyed and 12 left-eyed subjects made word/nonword decisions about stimuli presented in the left and right visual field under binocular, left-eye alone, and right-eye alone viewing conditions. Both accuracy (d') and response time measures were recorded. The nasal hemiretina advantage for response time and temporal hemiretina advantage for accuracy found for face recognition (Proudfoot, 1983, Brain and Cognition, 2, 25-31) were not present when lexical decisions were made. An overall right visual field advantage was present for both eye-dominance groups. The results support a hemispheric interpretation of visual field differences for the processing of words during lexical decision.

Adolescent↗

PubMed1988

Adult age differences in implicit and explicit memory: time course and encoding effects.

Young and older adults were tested at three delays on word-stem completion or cued recall following semantic or structural word judgments. Identical three-letter stems were present at retrieval for both implicit (completion) and explicit (cued recall) tasks; only the intention to recall list words differed. The young adults outperformed the older adults on both implicit and explicit tasks at all test delays. Under some conditions, the older but not the young adults performed more poorly on cued recall than on stem completion, suggesting a possible failure to use implicitly available information to support explicit remembering. These results suggest that some forms of implicit memory decline with normal aging.

Adolescent↗

PubMed1987

Visual field effects for processing content and function words.

This study investigated the processing of content and function words when input to the left vs right hemispheres. For both lexical decision and naming there was a larger RVF advantage for function as compared to content words: function words were processed more slowly than content in the LVF, but not in the RVF. These results do not replicate the previous report of Bradley and Garrett, Neuropsychologia 21, 155-159, 1983, and provide some support for the view that function words are less accessible to the right hemisphere. In a second experiment, there was no difference in VF asymmetry when acceptability judgments were required for function vs content word phrases. Grammaticality judgments, of any sort, may be predominantly processed in the left hemisphere.

Female↗

PubMed1987

Semantic priming with abstract and concrete words: differential asymmetry may be postlexical.

We investigated whether abstract and concrete words would be differentially effective in priming lexical decisions to words presented to the right and left visual fields. Under low probability prime conditions, where priming is presumed to reflect a spreading activation process within the lexicon, equivalent priming was obtained in each VF for both abstract and concrete primes. However, when the same words were used in a high probability prime paradigm, abstract primes were much less effective in the LVF than in the RVF, while priming with concrete words did not differ across the visual fields. Since such priming may reflect a postlexical semantic integration stage, the results imply that hemisphere differences for processing abstract and concrete words may arise only after lexical access has occurred, when semantic information retrieved from the lexicon becomes available for subsequent processing.

Adult↗

PubMed1986

Lexical judgments after right- or left-hemisphere injury.

Patients with unilateral left- or right-hemisphere lesions were asked to make similarity judgments to visually presented words on the basis of rhyme, meaning or visual similarity. The left-hemisphere-injured group was significantly impaired, relative to controls, for all types of lexical judgments, with the greatest impairment in the rhyme condition. Patients with right-hemisphere injury were also impaired, but only when lexical judgments were based on meaning. The results are generally consistent with normal and split-brain lateralization findings, and provide evidence supportive of a right-hemisphere contribution to some aspects of lexical semantic processing.

Aged↗

PubMed1986

Viewing conditions and hemisphere asymmetry for the lexical decision.

Exposure duration, retinal eccentricity and stimulus size were systematically varied to assess the contribution of viewing conditions to the lexical decision asymmetry. Contrary to Sergent's hypothesis (Psychol. Bull. 93, 481-512), the RVF advantage was unaltered over the range of conditions tested. This suggests that hemisphere differences in the ability to extract information from degraded signals cannot account for the asymmetry in this task. The results are compatible with the view that the lexical decision asymmetry arises from a relatively late stage of processing in which the information is no longer represented in sensory form.

Functional Laterality↗

PubMed1985

Hemisphere dynamics in lexical access: automatic and controlled priming.

Hemisphere differences in lexical processing may be due to asymmetry in the organization of lexical information, in procedures used to access the lexicon, or both. Six lateralized lexical decision experiments employed various types of priming to distinguish among these possibilities. In three controlled (high probability) priming experiments, prime words could be used as lexical access clues. Larger priming was obtained for orthographically similar stimuli (BEAK-BEAR) when presented to the left visual field (LVF). Controlled priming based on phonological relatedness (JUICE-MOOSE) was equally effective in either visual field (VF). Semantic similarity (INCH-YARD) produced larger priming for right visual field (RVF) stimuli. These results suggest that the hemispheres may utilize different information to achieve lexical access. Spread of activation through the lexicon was measured in complementary automatic (low probability) priming experiments. Priming was restricted to LVF stimuli for orthographically similar words, while priming for phonologically related stimuli was only obtained in the RVF. Automatic semantic priming was present bilaterally, but was larger in the LVF. These results imply hemisphere differences in lexical organization, with orthographic and semantic relationships available to the right hemisphere, and phonological and semantic relations available to the left hemisphere. Support was obtained for hemisphere asymmetries in both lexical organization and directed lexical processing.

Adolescent↗

PubMed1985

The eyes have it: exposure times and saccadic movements in visual half-field experiments.

Several tachistoscopic visual half-field experiments using exposure times in excess of 150 msec have been reported and arguments have been put forth justifying this procedure. An experiment was done investigating visual field accuracy under conditions where eye movement was allowed, following parafoveal exposure. Two control experiments were done to evaluate the viewing conditions. When eye movement is permitted, accuracy in both visual fields reaches 100%. It is concluded that visual field differences found with exposure times greater than 150 msec are due to the active cooperation of the subjects and not due to the justifications advanced by experimenters using long exposure times.

Adolescent↗

PubMed1985

Orienting attention within visual fields: how efficient is interhemispheric transfer?

Five experiments are reported examining the effect of attentional orienting on lexical decisions within visual half-fields. In Experiment 1, following baseline performance, subjects were instructed to improve performance to the right or left of the fixation point. In Experiment 2, trials were run in blocks with all items to one side of the fixation point. In Experiment 3, completely valid position indicators as to the location of the next item to be shown were presented prior to the stimulus item. In Experiment 4, to examine practice effects, no instructions or cuing were given to subjects. In Experiment 5, subjects were urged to improve performance, but with no instructions as to location. As a summary of our results, it can be stated that (a) consistent visual field differences in lexical decision performance are present, even when subjects were informed, prior to viewing, of the spatial location of the next stimulus item. (b) Lexical decision information initially input to one cerebral hemisphere is primarily processed in that hemisphere. Interhemispheric transfer of this type of language information seems to be done primarily as the end product of a cognitive process.

Attention↗

PubMed1985

Automatic and controlled semantic priming: accuracy, response bias, and aging.

Adult age differences in automatic and controlled semantic priming were investigated by varying the probability of valid primes in a lexical decision task. Tachistoscopic parafoveal stimulus presentation was used to assess age differences in accuracy and response bias as well as latency. Both age groups showed the expected findings of benefits without costs under automatic priming and benefits and costs under controlled priming. Errors for young adults were distributed equally among word and nonword stimuli, whereas older adults displayed a strong tendency to commit errors on nonword trials.

Adolescent↗