Poster B46, Tuesday, August 20, 2019, 3:15 – 5:00 pm, Restaurant Hall
Neither ipsilateral, nor contralateral pathway advantage for early compound decomposition: Evidence from anaglyphs
Roberto G. de Almeida1, Shirley Dumassais1;1Concordia University
Most studies on the role of morphological analysis in word recognition have suggested that compounds such as FOOTBALL are decomposed into its constituent morphemes FOOT and BALL. In fact, most models of word recognition incorporate either a single morphological decomposition route or allow for morphological decomposition to occur after the word has been initially recognized in full (e.g., Libben & de Almeida, 2002). We investigated the earliest moments of visual word recognition, when the retinal information--by hypothesis split vertically along the fovea--is divided into two visual pathways, projecting the right visual field into the left hemisphere (LH), and the left visual field into the right hemisphere (RH) (e.g., Brysbaert et al., 2012). While contralateral (nasal) projections are taken to be stronger than ipsilateral (temporal) ones (Obregon & Shillcock, 2012) for word recognition, compounds provide for an opportunity to understand how these early retinal projections interact with posterior representations involved in word identification (e.g., the visual word form area; Cohen et al., 2000). Thus, binocular fixation on the morpheme boundary of a bimorphemic compound should yield the following projections: the compound head (e.g., BALL), carrying most syntactic and semantic information, is projected to the language dominant LH, while the modifier (e.g., FOOT) is projected to the RH, allowing for a “head-start” in constituent access and semantic composition. We manipulated compound recognition using a novel masked presentation technique involving words colored in blue and red (or in black, as baseline) while subjects wore red/blue anaglyph glasses. We aimed to understand (a) the potential differences between ipsilateral and contralateral projections, (b) the sensitivity of these projections to different types of linguistic stimuli, and (c) how early visual word forms can be detected as potential morphemes of natural language via legal and illegal splits of the stimuli. Forty-six native English speakers participated in a masked lexical decision task. The stimuli were 168 words of the following types: (1) compounds (ex: BLACKBIRD, FOOTBALL), (2) pseudo compounds (e.g., CARPET, HAMMOCK) and (3) monomorphemic words (VACCINE, JINGLE). The stimuli were presented in three color combinations, all black, red/blue, and blue/red. For the red/blue and blue/red conditions, the colors were split either at the morpheme boundary (legal split) or at a character to the left or to the right of the split (illegal split). Trials consisted of a fixation (1000ms), a forward mask (500 ms), and the word/nonword (40ms). Data were analyzed by conducting a linear mixed effects (LME) model. The model with a fixed effect of the interaction between pathway and split type was compared to a null model consisting of only random predictors and was found to provide a statistically significant better fit to the data, χ2(5) = 33.24, p < 0.001. Multiple comparisons with Tukey’s correction reveal a legality effect (constituent morphemes faster than non-constituents), but no differences between ipsilateral and contralateral projections, p = 0.0152. While ipsilateral and contralateral pathways do not differ, our results suggest that at its earliest processing stages the visual word recognition system is sensitive to morphological properties of words.
Themes: Morphology, Reading
Method: Behavioral