Neighbour priming in eye movements during reading Kevin Paterson University of Leicester Samantha McCormick Royal Holloway, University of London Colin Davis Royal Holloway, University of London Simon Liversedge University of Southampton

Lexical Priming in Eye Movements o o Orthographic similarity between words affects performance in studies of isolated word recognition. o o Are similar effects observed for words read normally in sentences? o o How do these effects influence eye movement behaviour?

Substitution Neighbours o o Widespread view that reading a word activates lexical entry for that word and for orthographically similar words, known as neighbours. o o A word’s neighbours traditionally defined as those words that can be formed by substituting one letter for another while preserving letter position and length (e.g., Coltheart et al.,1977). e.g., “tank” has “rank”, “sank”, “task”, etc. as neighbours.

Addition & Deletion Neighbours o o Can also define neighbours in terms of words created by adding or deleting letters. (e.g., De Moor & Brysbaert, 2000; Davis, Perea, & Acha, 2009). o o For example: “public” is an addition neighbour of “pubic” “water” is a deletion neighbour of “waiter”.

Isolated Word Recognition o o Words with HF neighbours identified more slowly than matched controls. (e.g., Carreiras et al., 1997; Davis et al., 2009; Davis & Taft, 2005; Grainger, 1990; Grainger et al., 1989; Huntsman & Lima, 1996). o o Neighbour word primes slow target word recognition. o o Masked Priming: Greater inhibition for HF primes. (e.g., Brysbaert, et al., 2000; Davis & Lupker, 2006; De Moor & Brysbaert, 2000; Segui & Grainger, 1990) o o Unmasked Priming: greater inhibition for LF primes. (Colombo, 1986; Lupker & Colombo, 1994; Segui & Grainger, 1990)

Eye Movement Studies   Words with HF neighbours have longer reading times and receive more regressions than controls. (e.g., Davis et al., 2009; Perea & Pollatsek, 1998; Pollatsek et al., 1999; Slattery, 2010)   Effect attributed to misidentification of target word.

Eye Movement Studies   Other research using boundary paradigm shows preview of HF neighbour can facilitate word processing, by activating letter representations shared with target. (Williams et al., 2006) He felt the cold sweet on his face. * He felt the cold sleet on his face. *

Present Studies o o Growing interest in whether lexical priming is observed between words read normally in sentences. (e.g., Carreiras et al., 2005; Frisson et al., 2009; Paterson et al., 2009, in press; Warren & Morris, 2009) o o Experiment 1: Substitution neighbour priming. o o Experiment 2: Addition/Deletion neighbour priming. o o Are effects inhibitory or facilitatory? o o What influence do they have on eye movements? o o What is the time course of effects?

Experiment 1: Substitution Neighbours o o Sentences contained prime-target pairs or control-target pairs matched for length and frequency. o o Primes / controls displayed normally earlier in sentence than targets (mean 1.8 words apart). o o Prime was higher or lower in frequency than target (HF = 316, LF = 8, p<.05). Paterson, Liversedge, & Davis, PB&R, 2009.

Stimuli   Low freq prime – high freq target There was a blur prime as the blue target lights spill-over of the police car whizzed down the street. There was a gasp control as the blue target lights spill-over of the police car whizzed down the street.   High freq prime – low freq target In the photograph, the blue prime lights were a blur target against spill- over the cold night. In the photograph, the town control lights were a blur target against spill- over the cold night.

Method & Procedure   Participants’ right eye movements recorded using DPI eye tracker at the University of Leicester.   48 sets of sentences (using word stimuli from Davis & Lupker, 2006).   40 participants from University of Leicester.

Target word reading times Robust inhibitory priming effects unaffected by prime-target frequency. First fixation durations: 12 ms effect (Fs>5.8). No interaction (Fs<1). Gaze durations: 15 ms effect (Fs>4). No interaction (Fs<1). Total reading times: 45 ms effect (Fs>8). No interaction. First Fixation Durations Gaze durations

Spill-over region   More regressions from post-target region when target follows neighbour (Fs>4). Interaction not significant.   Evidence for misidentification of target words?

Summary o Prior exposure to word’s neighbour earlier in a sentence slows subsequent processing of that word. o Effect is observed in eye movement measures associated with early word processing. o Priming influences decisions about when to move the eyes during reading. o Unlike in word recognition research, effect was not modulated by prime-target frequency.

Experiment 2: Addition / Deletion Neighbours Are inhibitory priming effects observed for addition and deletion neighbours? public-pubicbeast-breast 2. Are effects influenced by the separation of prime and target words in the sentence?

  3 factors manipulated:   Primes were LF neighbours of targets or non-neighbours.   Primes & targets were close together or further apart in sentence.   Neighbour primes were addition or deletion neighbours.   Created by adding/deleting an interior letter.   Deletion: prime = beast, target = breast   Addition: prime = window, target = widow   60 sets of sentences (30 deletion, 30 addition)   56 participants from University of Leicester. Method

stimuli Close prime-target pairs The beast prime at his breast target looked scary and was desperate for a meal The snake control at his breast target looked scary and was desperate for a meal. Distant prime-target pairs The beast prime that sat quivering at his breast target looked scary and was desperate for a meal The snake control that sat quivering at his breast target looked scary and was desperate for a meal.

Target word reading times Inhibitory effect for addition neighbour primes only, that is larger when words are closer together.

Target word reading times Similar effects for addition and deletion neighbours.

Target word reading times Again, similar effects for addition and deletion neighbours.

Spill-over Region Further evidence for target word misidentification.

Regressions to Target Word

Summary & Conclusions o Further evidence of inhibitory neighbour priming. o Observed in range of eye movement measures, but effect emerges earliest in eye movement record for addition neighbour primes. o May reflect competitive advantage for longer words. o Effects for both close and distant targets, but disruption greater when words are close together. o Together, the studies clearly demonstrate that eye movements are sensitive to intra-sentential, inter-lexical influences that occur naturally within sentences.

Target Word Reading Times  Inhibitory priming effect for close prime-target pairs only (21 ms effect, interaction Fs>6).

Target Word Reading Times Inhibitory priming effect for both close and distant prime- target pairs (14 ms prime effect, Fs>7; interaction Fs<1).

Target Word Reading Times Inhibitory priming effect for both close and distant prime- target pairs (prime effect Fs>16; interaction Fs>6).

Spill-over Region Effects More regressions from spill-over region when target followed close or distant neighbour prime (Fs>15).

What is the underlying mechanism?

Effect due to spreading activation in mental lexicon. A prime word activates its lexical entry and lexical entries for related words. This activation decays over time. However, there is sufficient ongoing activation to produce orthographic priming.

This is an episodic memory effect. When prime and target words are read separately, target word processing evokes an episodic memory trace encoded during prime word processing, and this affects word identification.

1. Decay in lexical activation The prime activates its lexical entry and lexical entries for related words. This activation decays rapidly, and would be expected to carry across just a few words in the sentence. 2. Episodic memory effect. Target word processing evokes an episodic memory trace encoded during prime word processing, and this affects word identification. Predicts longer lasting priming effects.