The Role of Underspecification in RC Attachment: Speed-accuracy tradeoff evidence

A number of studies have found evidence for the so-called ambiguity advantage, i.e., a speed-up in processing ambiguous sentences compared to their unambiguous counterparts. While a number of proposals regarding the mechanism underlying this phenomenon have been made, the empirical evidence so far is far from unequivocal. It is compatible with several theories, including strategic underspecification (Swets et al., 2008), race models (Van Gompel et al., 2000; Logacev and Vasishth, 2016), and a more recentcoactivation-based account (Dillon et al., 2019). While all three classes of theories make matching predictions for the average time to complete RC attachment in ambiguous compared to unambiguous sentences, their predictions diverge with regard to theminimum completion times. I used the speed-accuracy tradeoff procedure to test the predictions of all three classesof theories. According to a hierarchical Bayesian model, the speed-accuracy tradeoff functions (SATFs) for different RC attachment conditions (high, low or ambiguous) show an earlier departure from chance performance in the ambiguous condition than in either of the unambiguous conditions. The results further indicate increased asymptotic accuracy but no increase in processing rate in the ambiguous condition. Taken together, this pattern of results is compatible with the strategic underspecification model, and to a lesser degree with coactivation based accounts.

Statistical Power in Response Signal Paradigm Experiments

Although not widely used, the speed-accuracy tradeoff (SAT) method has produced several prominent findings in sentence processing. While a substantial number of SAT studies has yielded statistical null-results regarding the degree to which certain factors influence the speed of sentence processing operations, the statistical power of the SAT paradigm is not known. As a result, it is not entirely clear how to interpret these findings. We addressed this problem by means of a simulation study in which we simulated SAT experiments for a range of known effect sizes in order to determine the statistical power in typical SAT experiments. We found that while SAT experiments appear to have quite satisfactory power to detect differences in asymptotic accuracy, that is not the case for speed-related parameters. We conclude that the failure to find an effect in speed-related parameters in SAT experiments may be less meaningful than previously thought.

An alternative formula for approximate extended Born inversion

Various modifications of reverse time migration (RTM) provide asymptotic inverses to the subsurface offset extended Born modeling operator for constant-density acoustics. These approximate inverses have the same quality (asymptotic accuracy) as do generalized Radon transform pseudoinverses, but they can be computed without any ray tracing whatsoever. We have developed an approximate inverse of this type whose additional computational cost, above that of subsurface offset extended RTM, is negligible.