The first letter position effect in visual word recognition: The role of spatial attention.

Abstract

A prominent question in visual word recognition is whether letters within a word are processed in parallel or in a left to right sequence. Although most contemporary models posit parallel processing, this notion seems at odds with well-established serial position effects in word identification that indicate preferential processing for the initial letter. The present study reports 4 experiments designed to further probe the locus of the first position processing advantage. The paradigm involved masked target words presented for short durations and required participants to subsequently select from two alternatives, one which was identical to the target and one that differed by a single letter. Experiment 1 manipulated the case between the target and the alternatives to ensure that previous evidence for a first position effect was not due to simple perceptual matching. The results continued to yield a robust first position advantage. Experiment 2 attempted to eliminate post-perceptual decision processes as the explanatory mechanism by presenting single letters as targets and requiring participants to select an entire word that contained the target letter at different positions. Here the first position advantage was eliminated, suggesting post-perceptual decision processes do not underlie the effect. The final two experiments presented masked stimuli either all vertically (Experiment 3) or randomly intermixed vertical and horizontal orientation (Experiment 4). In both cases, a robust first position advantage was still obtained. We consider alternative interpretations of this effect and suggest that these results are consistent with a rapid deployment of spatial attention to the beginning of a target string which occurs post-stimulus onset.

Stimulus orientation and the first-letter advantage

“…These results are in line with the predictions of the MRF hypothesis, according to which a first-position advantage should be more pronounced for letter strings than symbol strings, and particularly so with horizontally aligned strings. However, the fact that a significant difference between letters and symbols at the first position was also found with vertically oriented stimuli, suggests that attention might be preferentially attracted to the beginning of letter strings independently of their orientation ( Aschenbrenner et al, 2017 ). Caution must nevertheless be exercised when drawing such a conclusion, since the interaction between Stimulus Type and Position only approached conventional significance under vertical presentation, and this remained the case even when only positions 1 and 2 were taken into consideration (see footnote 3 ).…”

“…These were a) target type (letters vs. symbols), b) target position (positions 1 to 5), and c) orientation of the array (horizontal vs. vertical). Following Aschenbrenner et al (2017) we used “marquee” style (i.e., stimuli remain upright) for the vertical presentation condition (see Fig. 1 ).…”

“…However, two recent studies have challenged the MRF hypothesis ( Aschenbrenner et al, 2017 , Castet et al, 2017 ). In the Aschenbrenner et al study, words were presented (33 or 50 ms) between visual masks.…”

“…The MRF hypothesis predicts a first position advantage exclusively for horizontally displayed strings of letters. The attentional account ( Aschenbrenner et al, 2017 ) predicts a first position advantage for both horizontal and vertical orientations, but whether the first position advantage for vertical displays selectively arises only for letter stimuli is an empirical question. The crucial comparison with symbols will shed light on the extent to which any observed first-position effects are related to orthographic processing, or are the result of generic processing mechanisms such as visual interference or memory scanning.…”

Orthographic and phonological priming effects in the same–different task.

“…It is arguable that the (orthographic as well as phonological) priming manipulation was not as strong as it could have been in that experiment because the critical letter was word-internal. Perceptual identification of a letter within a string is generally worse for internal positions and best for the initial position (see, e.g., Aschenbrenner, Balota, Weigand, Scaltritti, & Besner, 2017 ), and in the masked onset priming manipulation (which has been shown to produce phonological priming effects in tasks involving phonology) it is always the first letter that is manipulated. In the present experiments, we therefore manipulated the first letter (e.g., cult/kult/nult/CULT).…”