4. Predictions & Results

1. Taking the Epistemic Step Richard Breheny1, Heather J Ferguson2, Napoleon Katsos3 1University College London, 2University of Kent, 3University of Cambridge r.breheny@ucl.ac.uk, (h.ferguson@kent.ac.uk, nk248@cam.ac.uk • 3. Method • 40 participants • 40 experimental trials (36 fillers) • Within-subjects (XXY, XX/Y, XX, X/X, XY) design • Order of description rotated so first-mentioned X move is last-occurring X move 50% of time • Fillers include first mention of conjunction • Order of transfer locations was counterbalanced across trials • Calculated probability of fixating Target vs. Alternative box as a function of time: log(P(Target) / P(Alternative)) • 1. Introduction • Conversational implicatures can be accessed on-line (Breheny et al., 2006; Sedivy et al., 1999) • This includes Quantity Implicatures. E.g., • 1. a. John ate some of the cookies • ==> b. John did not eat all of the cookies • 2. a. John put a book on the shelf • ==> b. John put nothing else on the shelf • A sample Gricean derivation for [2b] is given in (I-V) below: • For all [2a] means, John could have put many other things on the shelf. • Given that the speaker is telling me what John put on the shelf and that he gives as much information as is relevant… • …this must be all the speaker knows on the question. • The speaker knows the full answer to the question • [2b] • This Gricean account has been challenged (Levinson, 2000; Chierchia et al., 2009) and questioned as the basis for on-line access of implicatures, given the rapidity of effects that have been found (Sedivy, 2003). • Previously, we established that QIslike [2] are accessed on-line by passing through step II above (Breheny et al., 2009) • Here we explore if QIs as in [2] are only derived where IV can be assumed – the Epistemic Step • 4. Predictions & Results • In line with Breheny et al. (2009), we predict a Target bias prior to disambiguating information “A/B” in XXY items • If Epistemic Step is really necessary, we predict no bias in XX/Y items • ANOVA • From [object] onset: Sig. difference between all conditions [all Fs > 5.99] • 2. The Study • Interactive visual world study • Two communicators watched short videos on separate computer monitors and then described the events to each other • After 8 practice trials where roles are rotated, the ‘speaker’ (confederate) and ‘hearer’ are chosen for rest of the trials • The Twist: On half the trials a screen blocked the speakers’ (but not the listeners’) view part-way through the video; Both communicators were explicitly aware of this manipulation • One-samplet-tests • From [object] onset: bias to correct target in XXY [ts > 2.69] • No bias in XX/Y condition [ts < 1.78] • Paired t-tests • Across all regions: No sig. difference between XX and XX/Y [all ts < 1.17]