Sereno, Sara (2018). Parafoveal magnification. [Data Collection]. Colchester, Essex: UK Data Archive. 10.5255/UKDA-SN-851291
In reading, during each eye fixation, only part of a text is available for processing as visual acuity drops off rapidly from the centre of fixation. About 6-8 characters of text typically fall within the fovea, or central high-acuity area of vision. Outside this area, the parafovea, visual acuity decreases the further the distance from fixation. Nevertheless, useful information is extracted parafoveally, as demonstrated in reading tasks where such information is denied and the reading rate is significantly slowed. The perceptual span is that region of text from which useful information can be extracted, extending from approximately 3 characters to the left to 14 characters to the right of fixation. The asymmetry of this span is taken to reflect attentional demands of reading – in left-to-right languages, like English, new information is located to the right of fixation. This proposal devises a 'parafoveal magnification' paradigm. Text will be modified contingent on the position of the reader’s fixation location with parafoveal information enlarged, functionally equalising its perceptual impact with concurrent foveal information. Results will address whether the limits of the perceptual span are due to purely visual constraints of acuity or to attentional constraints of reading.
Data description (abstract)
The question this proposal addresses is whether the limits of the perceptual span is due to purely visual constraints of parafoveal acuity or to attentional constraints of reading. By implementing a new reading paradigm, it is possible to separate the contributions of acuity and attention. Specifically, displayed text was modified contingent on the position of the reader’s fixation location such that parafoveal information is magnified. We call this the “parafoveal magnification” (PM) paradigm because parafoveal information appears larger, functionally equalising its perceptual impact with concurrent foveal information.
After implementing PM software, we ran and analysed two experiments. In Experiment 1, participants’ eye movements were monitored while reading normal and PM text. We additionally manipulated window size (7-, 14-, or 21-character window, or no-window). Releasing the constraints of visual acuity via PM allowed us to assess whether the attentional span in reading is equivalent to the “perceptual span” as assessed by prior experiments. Finally, we repeated a set of sentences under normal and PM presentation conditions (normal-then-PM vs. PM-then- normal). Experiment 2 investigated the parafoveal-on-foveal effect – in which the ease or difficulty in processing word n+1 is reflected in the fixation duration on word n. In this experiment, we manipulated both the word frequency and plausibility of target words in sentences that were presented with PM.
Although PM induced physically longer saccades (in pixels) versus normal text, the saccade length in terms of number of characters was the same in both situations. Thus, the attentional span seems to be delineated in terms of amount of information rather than a physical metric (visual angle). These results confirm that the perceptual span seems to be limited by attentional rather than visual constraints. The physical size of the attentional span adapts to the amount of information to process. Finally, our results indicate that readers are able to immediately adapt their saccadic programs depending on the display type.
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Sponsors: | Economic and Social Research Council | ||||||
Grant reference: | RES-000-22-1907 | ||||||
Topic classification: | Psychology | ||||||
Project title: | Parafoveal magnification: A new paradigm for reading research | ||||||
Grant holders: | Sara Crescentia Sereno, Patrick Joseph O'Donnell, Sebastien Miellet | ||||||
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Date published: | 25 Apr 2014 06:52 | ||||||
Last modified: | 03 Oct 2018 12:41 | ||||||