Dual-task studies assessed the effects of cellular-phone conversations on performance of a simulated driving task. Performance was not disrupted by listening to radio broadcasts or listening to a book on tape. Nor was it disrupted by a continuous shadowing task using a handheld phone, ruling out, in this case, dual-task interpretations associated with holding the phone, listening, or speaking, However significant interference was observed in a word-generation variant of the shadowing task, and this deficit increased with the difficulty of driving. Moreover unconstrained conversations using either a handheld or a hands-free cell phone resulted in a twofold increase in the failure to detect simulated traffic signals and slower reactions to those signals that were detected. We suggest that cellular-phone use disrupts performance by diverting attention to an engaging cognitive context other than the one immediately associated with driving.

This research examined the effects of hands-free cell phone conversations on simulated driving. The authors found that these conversations impaired driver's reactions to vehicles braking in front of them. The authors assessed whether this impairment could be attributed to a withdrawal of attention from the visual scene, yielding a form of inattention blindness. Cell phone conversations impaired explicit recognition memory for roadside billboards. Eye-tracking data indicated that this was due to reduced attention to foveal information. This interpretation was bolstered by data showing that cell phone conversations impaired implicit perceptual memory for items presented at fixation. The data suggest that the impairment of driving performance produced by cell phone conversations is mediated, at least in part, by reduced attention to visual inputs.

Items seen for the second time in an experiment (old items) can be perceived more readily (fluently) than items seen for the first time (new items) (e.g., Jacoby & Dallas, 1981). We hypothesized that perceptual fluency is used as a cue for discriminating old from new items. In the test phase of a recognition task, each item was gradually clarified until it was identified, at which time subjects made an old/new judgment. We expected that fluently perceived (quickly identified) items would tend to be judged old regardless of their actual old/new status. In Experiment 1, words were more likely to be judged old both if they were quickly identified and, independently of this, if they actually were old. The latter finding implicates a factor (e.g., directed memory search) other than perceptual fluency in recognition judgments. Experiment 2 succeeded in reducing the contribution of this additional factor by using nonwords rather than words. Recognition judgments for nonwords were much more dependent on speed of identification than they were on actual old/new status. We propose that perceptual fluency is the basis of the feeling of familiarity and is one of two important factors that make variable contributions to recognition judgments. We thank Teresa A. Weber for her assistance in conducting Experiment 2.

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The mind appears to be biased simultaneously toward both expected and unexpected inputs. For example, familiar scenes are usually perceived more readily than novel scenes, indicating the former bias, but a single novel object sometimes pops out from a familiar field, indicating the latter bias. A diverse literature and a computational model converge on the following resolution to this paradox: The former bias is conceptually driven and actually suppresses data-driven processing of expected inputs; in turn, this suppression disinhibits data-driven processing of unexpected inputs, yielding the latter bias. Evidence for suppressed data-driven processing of expected inputs is drawn from studies of perceptual habituation, semantic satiation, memory inhibition, inhibition of return, repetition blindness, primed inhibition, the word-inferiority effect, registration without learning, and both expert-and schema-based inhibitory effects. Evidence for enhanced data-driven processing of unexpected inputs is drawn from studies of the orienting response, mismatch negativity, memory facilitation, both expert-and schema-based facilitatory effects, and perceptual popout. The model, called mismatch theory, incorporates inhibitory and facilitatory perceptual dynamics and is found to simulate the opposing biases. Implications of mismatch theory for perceptual phenomenology, dynamic systems theory, mental health, and individual differences are also discussed.In a review of some of her research on perception and memory, Treisman (1992) concluded that by creating accumulated traces of past perceptual objects or events, the world molds our minds to recreate earlier experiences. At the same time, we retain an impressive capacity also to represent any new object that fails to find its match in our prior assembly of stored tokens. (p. 874) This observation echoes what Grossberg (1987) calls the stability-plasticity dilemma. How can the mind be molded to familiar environments and still remain vigilant for change? We suggest that the'opposing biases toward both what is most expected and what is least expected are among the most adaptive and revealing features of the mind. Part 1 of this paper presents a paradigmatic example of opposing mental biases in the form of our own prior work on novel popout. Part 2 outlines in general terms a possible explanation of novel popout and resolution of the stability-plasticity dilemma, called mismatch theory. Part 3 draws together diverse lines of empirical support for the key assumptions of mismatch theory. Part 4 de-