Statistical analysis for finger tapping with a periodic external stimulus

In this paper we outline an experiment in which seven subjects attempted to tap in synchrony with a pacing stimulus with the interstimulus interval that varied in a cycle (T,T+dT,T, T-dT) repeating every fourth interval, where T represents an unexpected step change of an interstimulus interval. Conditions included three levels of T= (400, 500, and 600 msec.) with four levels of dT= 1, 3, 5, and 7% of T). The statistical analysis indicated that small changes in T lead to rapid matching of the interresponse intervals to the new interstimulus intervals even when the variation in the input is not apparent to subjects.     

Associative interference in recognition memory: A dual-process account

Associative interference from overlapping word pairs (A-B, A-D) reduces recall but has inconsistent effects on recognition. A dual-process account suggests that interference conditions reduce recollection but increase familiarity. This is predicted to increase recognition false alarms but have variable effects on recognition hits, depending on the relative contribution of recollection and familiarity. In three experiments that varied materials (sentences or random nouns) and test type (associative or pair recognition), interference conditions always increased recognition false alarms, but sometimes increased and sometimes decreased recognition hits. However, remember hits always decreased and know hits always increased with interference, patterns predicted of the recollection and familiarity processes, respectively. According to the dual-process view, a manipulation that affects the component processes in opposite ways can produce inconsistent patterns of recognition performance as the relative contribution of recollection and familiarity changes across tasks.     

Race and information processing in criminal trials: does the defendant's race affect how the facts are evaluated?

Two studies examined whether a criminal defendant's race influences Whites' sensitivity to legally relevant information. In Study 1, prosecution case strength ratings and guilt likelihood ratings were more sensitive to the strength of the defendant's alibi when he was Black than when he was White, if the experimental task was designed to elicit low processing motivation. Under high motivation, participants were equally sensitive to alibi strength, regardless of defendant race. In Study 2, the alibi strength manipulation was replaced with a manipulation of the effectiveness of the district attorney's cross-examination. As predicted, defense case strength ratings were more sensitive to the strength of the prosecutor's cross-examination with a Black defendant than with a White defendant-under low motivation. Under high motivation, sensitivity did not depend on defendant race. These results suggest that a Black defendant can elicit greater sensitivity to legally relevant information than will a White defendant.     

Shape-from-shading depends on visual, gravitational, and body-orientation cues

The perception of shading-defined form results from an interaction between shading cues and the frames of reference within which those cues are interpreted. In the absence of a clear source of illumination, the definition of 'up' becomes critical to deducing the perceived shape from a particular pattern of shading. In our experiments, twelve subjects adjusted the orientation of a planar disc painted with a linear luminance gradient from one side to the other, until the disc appeared maximally convex-that is, until the luminance gradient induced the maximum perception of a three-dimensional shape. The vision, gravity, and body-orientation cues were altered relative to each other. Visual cues were manipulated by the York Tilted Room facility, and body cues were altered by simply lying on one side. The orientation of the disc that appeared maximally convex varied in a systematic fashion with these manipulations. We present a model in which the direction of perceptual 'up' is determined from the sum of three weighted vectors corresponding to the vision, gravity, and body-orientation cues. The model predicts the perceived direction of 'up', contributes to our understanding of how shape-from-shading is deduced, and also predicts the confidence with which the 'up' direction is perceived.     

Conceptual development and conversational understanding

Children's understanding of the implications of conversation can influence their responses on tasks designed to measure conceptual development. These responses are in keeping with developmental changes in the ability to recognize and resolve ambiguity in communicative contexts, as shown, for example, in children's ability to compute "scalar implicatures". Examining steps children take to overcome difficulties in processing the relevant features of tasks and in correctly interpreting task instructions promise to illuminate mechanisms of conceptual development. We review recent research in this area, focussing on early knowledge of the appearance-reality distinction and knowledge of cosmological concepts.     

The old and thee, uh, new: disfluency and reference resolution

Most research on the rapid mental processes of on-line language processing has been limited to the study of idealized, fluent utterances. Yet speakers are often disfluent, for example, saying "thee, uh, candle" instead of "the candle." By monitoring listeners' eye movements to objects in a display, we demonstrated that the fluency of an article ("thee uh" vs. "the") affects how listeners interpret the following noun. With a fluent article, listeners were biased toward an object that had been mentioned previously, but with a disfluent article, they were biased toward an object that had not been mentioned. These biases were apparent as early as lexical information became available, showing that disfluency affects the basic processes of decoding linguistic input.     

How dogs navigate to catch frisbees

Using micro-video cameras attached to the heads of 2 dogs, we examined their optical behavior while catching Frisbees. Our findings reveal that dogs use the same viewer-based navigational heuristics previously found with baseball players (i.e., maintaining the target along a linear optical trajectory, LOT, with optical speed constancy). On trials in which the Frisbee dramatically changed direction, the dog maintained an LOT with speed constancy until it apparently could no longer do so and then simply established a new LOT and optical speed until interception. This work demonstrates the use of simple control mechanisms that utilize invariant geometric properties to accomplish interceptive tasks. It confirms a common interception strategy that extends both across species and to complex target trajectories.