Hemispheric asymmetry in holistic processing of words.

Holistic processing has been regarded as a hallmark of face perception, indicating the automatic and obligatory tendency of the visual system to process all face parts as a perceptual unit rather than in isolation. Studies involving lateralized stimulus presentation suggest that the right hemisphere dominates holistic face processing. Holistic processing can also be shown with other categories such as words and thus it is not specific to faces or face-like expertize. Here, we used divided visual field presentation to investigate the possibly different contributions of the two hemispheres for holistic word processing. Observers performed same/different judgment on the cued parts of two sequentially presented words in the complete composite paradigm. Our data indicate a right hemisphere specialization for holistic word processing. Thus, these markers of expert object recognition are domain general.

The relation between holistic processing as measured by three composite tasks and face processing: A latent variable modeling approach.

We investigated the relationship between holistic processing and face processing using a latent variables approach. Three versions of the composite paradigm were used to measure holistic processing: Vanderbilt Holistic Face Processing Test, a sequential composite matching task, and a simultaneous composite matching task. Three tasks were used to measure face perception and face memory abilities respectively. We had three pairs of tasks such that within each pair (of memory and perception task), the stimuli involved, the requirement for matching across viewpoints, etc., are the same, such that the only difference is whether perception or memory is taxed. There were no significant correlations between the different versions of the composite task. We discovered no evidence to support a distinction between face perception and face memory, suggesting the existence of a general face processing factor. Finally, there was no evidence that holistic processing (as captured by either of the three composite tasks) is predictive of better face processing per se, casting doubts on the role of holistic processing in differentiating different levels of efficiency in face processing.

The relationships between reading fluency and different measures of holistic word processing.

Recently, paradigms in the face recognition literature have been adopted to reveal holistic processing in word recognition. It is unknown, however, whether different measures of holistic word processing share similar underlying mechanisms, and whether fluent word reading relies on holistic word processing. We measured holistic processing effects in three paradigms (composite, configural sensitivity, part-whole) as well as in reading fluency (3DM task: reading aloud high- and low-frequency words and pseudowords). Bin scores were used to combine accuracy and response time variables in the quest for a more comprehensive, reliable, and valid measure of holistic processing. Weak correlations were found between the different holistic processing measures, with only a significant correlation between the configural sensitivity effect and part-whole effect (r = .32) and a trend of a positive correlation between the word composite effect and configural sensitivity effect (r = .21). Of the three holistic processing measures, only one (part-whole effect) correlated with a lexical access measure of 3DM (r = .23). We also performed a principal component analysis (PCA) of performance in the three lists of 3DM, with the second most probably reflecting lexical access processes. There was a tendency for a positive correlation between part-whole bin measure and Component 2 of PCA. We also found a positive correlation between composite aligned in accuracy and Component 2 of PCA.Our results show that different measures of holistic word processing reflect predominantly different mechanisms, and that differences among normal readers in word reading do not seem to depend highly on holistic processing.

Children process faces holistically with the same efficiency as adults.

Previous studies had reported qualitatively identical holistic face processing (using the composite task) already in 6-year-olds. In the present study, we evaluated these processes quantitatively by evaluating whether children are less efficient in dealing with and encoding faces. Thus, in the present study we explored the time course of holistic processing in children and adults by manipulating stimulus presentation time. The study composite task was presented for 800 ms. The test composite face was presented either for 183 ms or 800 ms. Our youngest participants, 6-year-olds, process faces holistically with the same efficiency as typical adults.

Further evidence for a late locus of holistic word processing: Exploring vertex effect in the word composite task.

Previous studies have shown a rather late and lexical level for holistic word processing. In the present study, we evaluated whether there are early effects in holistic processing of words, taking into consideration the role of lower-level visual processes that are critical in the hierarchy of visual word recognition: the extraction of viewpoint-invariant line junctions/vertices. We used contour-deleted words in two conditions: preservation of the vertices versus preservation of midsegments and an all-contour condition. We found evidence of a composite effect that was equivalent for all materials. Thus, we found no evidence of an early contribution of holistic processing to word recognition, and confirmed that holistic word processing is related to late lexical orthographic representations.

Holistic word processing is correlated with efficiency in visual word recognition.

Holistic processing of visual words (i.e., obligatory encoding of/attending to all letters of a word) could be a marker of expert word recognition. In the present study, we thus examined for the first time whether there is a direct relation between the word-composite effect (i.e., all parts of a visual word are fully processed when observers perform a task on a word part) and fast access to the orthographic lexicon by visual word experts (i.e., fluent adult readers). We adopted an individual differences approach and used the word-frequency effect (i.e., faster recognition of high- than low-frequency words) in an independent lexical decision task as a proxy of fast access to lexical orthographic representations. Fluent readers with larger word-composite effect showed smaller word-frequency effect. This correlation was mainly driven by an association between a larger composite effect and faster lexical decision on low-frequency words, probably because these lexical representations are less stable and integrated/unitized, hence allowing differentiating among fluent readers. We thus showed that holistic processing of visual words is indeed related to higher efficiency in visual word recognition by skilled readers.