Eye movements during intentional car following

Does intentional car following capture visual attention to the extent that driving may be impaired? We tested fifteen participants on a rudimentary driving simulator. Participants were either instructed to follow a vehicle ahead through a simulated version of London, or were given verbal instructions on where to turn during the route. The presence or absence of pedestrians, and the simulated time of the drive (day or night) were varied across the trials. Eye movements were recorded along with behavioural measures including give-way violations, give-way accidents, and kerb impacts. The results revealed that intentional car following reduced the spread of search and increased fixation durations, with a dramatic increase in the time spent processing the vehicle ahead (controlled for exposure). The effects were most pronounced during nighttime drives. During the car-following trials participants were also less aware of pedestrians, produced more give-way violations, and were involved in more give-way accidents. The results draw attention to the problems encountered during car following, and we relate this to the cognitive demands placed on drivers, especially police drivers who often engage in intentional car following and pursuits.     

Index of suspicion: feeling not believing

Throughout the U.S., state laws require professionals who work with children to report cases of suspected child abuse to child protection services. Both practically and conceptually, however, significant problems arise from a lack of clarity regarding the threshold that has been set for reporting. Specifically, there is no consensus as to what constitutes reasonable suspicion, and little direction for how mandated reporters should gauge their legal and professional responsibilities when they harbor suspicion. In this paper we outline the context of the problem, discuss the nature and scope of its conceptual underpinnings, and offer recommendations for moving towards a concrete, practical solution.     

Reversal of motor learning in the vestibulo-ocular reflex in the absence of visual input

Motor learning in the vestibulo-ocular reflex (VOR) and eyeblink conditioning use similar neural circuitry, and they may use similar cellular plasticity mechanisms. Classically conditioned eyeblink responses undergo extinction after prolonged exposure to the conditioned stimulus in the absence of the unconditioned stimulus. We investigated the possibility that a process similar to extinction may reverse learned changes in the VOR. We induced a learned alteration of the VOR response in rhesus monkeys using magnifying or miniaturizing goggles, which caused head movements to be accompanied by visual image motion. After learning, head movements in the absence of visual stimulation caused a loss of the learned eye movement response. When the learned gain was low, this reversal of learning occurred only when head movements were delivered, and not when the head was held stationary in the absence of visual input, suggesting that this reversal is mediated by an active, extinction-like process.     

Why is it difficult to see in the fog? How stimulus contrast affects visual perception and visual memory

Processing visually degraded stimuli is a common experience. We struggle to find house keys on dim front porches, to decipher slides projected in overly bright seminar rooms, and to read 10th-generation photocopies. In this research, we focus specifically on stimuli that are degraded via reduction of stimuluscontrast and address two questions. First, why is it difficult to process low-contrast, as compared with high-contrast, stimuli? Second, is the effect of contrastfundamental in that its effect is independent of the stimulus being processed and the reason for processing the stimulus? We formally address and answer these questions within the context of a series of nested theories, each providing a successively stronger definition of what it means for contrast to affect perception and memory. To evaluate the theories, we carried out six experiments. Experiments 1 and 2 involved simple stimuli (randomly generated forms and digit strings), whereas Experiments 3–6 involved naturalistic pictures (faces, houses, and cityscapes). The stimuli were presented at two contrast levels and at varying exposure durations. The data from all the experiments allow the conclusion that some function of stimulus contrast combines multiplicatively with stimulus duration at a stage prior to that at which the nature of the stimulus and the reason for processing it are determined, and it is the result of this multiplicative combination that determines eventual memory performance. We describe a stronger version of this theory— the sensory response, information acquisition theory—which has at its core, the strong Bloch’s-law-like assumption of a fundamental visual system response that is proportional to the product of stimulus contrast and stimulus duration. This theory was, as it has been in the past, highly successful in accounting for memory for simple stimuli shown at short (i.e., shorter than an eye fixation) durations. However, it was less successful in accounting for data from short-duration naturalistic pictures and was entirely unsuccessful in accounting for data from naturalistic pictures shown at longer durations. We discuss (1) processing differences between short- and long-duration stimuli, (2) processing differences between simple stimuli, such as digits, and complex stimuli, such as pictures, (3) processing differences between biluminant stimuli (such as line drawings with only two luminance levels) and multiluminant stimuli (such as grayscale pictures with multiple luminance levels), and (4) Bloch’s law and a proposed generalization of the concept ofmetamers.     

Senior capstone design and ethics: A bridge to the professional world

A senior level capstone design experience has been developed and offered with a particular emphasis on many of the professional issues raised in Accreditation Board for Engineering and Technology (ABET) Engineering Criterion IV. The course has sought to develop student awareness of the ethical foundation of the engineering profession, the global and societal framework within which engineers practice, and the environmental impact on engineering. The capstone design course also focused upon improving the technical communications skills of the graduating senior class with both extensive instruction in writing and multiple workshops dealing with the art of making an effective oral presentation. The effectiveness of the design course was assessed using Kirkpatrick’s model for evaluating training programs. An earlier version of this paper was presented at the “Ethics and Social Responsibility in Engineering and Technology” meeting, New Orleans, 2003.     

The US-preexposure effect in lithium-induced flavor-aversion conditioning is a consequence of blocking by injection cues

In 2 experiments, rats received flavor-aversion conditioning in which the unconditioned stimulus (US) was an orally consumed solution of lithium chloride (LiCl). The resulting aversion was not attenuated by giving preexposure to injections of LiCl, although such preexposure did attenuate aversions established using injected LiCl as the US (Experiment 1). This outcome suggests that blocking by injection-related cues is responsible for the US-preexposure effect observed in this situation. Experiment 2 confirmed this interpretation by showing that presenting such cues (by giving an injection of saline) at the time that the LiCl was drunk resulted in an attenuation of conditioning in animals preexposed to injections of LiCl. The US-preexposure effect obtained in these experiments can be explained solely in terms of blocking by injection cues, although other mechanisms may contribute to the effect seen in other flavor-aversion paradigms.     

Assessing model mimicry using the parametric bootstrap

We present a general sampling procedure to quantify model mimicry, defined as the ability of a model to account for data generated by a competing model. This sampling procedure, called the parametric bootstrap cross-fitting method (PBCM; cf. Williams (J. R. Statist. Soc. B 32 (1970) 350; Biometrics 26 (1970) 23)), generates distributions of differences in goodness-of-fit expected under each of the competing models. In the data informed version of the PBCM, the generating models have specific parameter values obtained by fitting the experimental data under consideration. The data informed difference distributions can be compared to the observed difference in goodness-of-fit to allow a quantification of model adequacy. In the data uninformed version of the PBCM, the generating models have a relatively broad range of parameter values based on prior knowledge. Application of both the data informed and the data uninformed PBCM is illustrated with several examples.     

The "saw-it-all-along" effect: demonstrations of visual hindsight bias

The authors address whether a hindsight bias exists for visual perception tasks. In 3 experiments, participants identified degraded celebrity faces as they resolved to full clarity (Phase 1). Following Phase 1, participants either recalled the level of blur present at the time of Phase 1 identification or predicted the level of blur at which a peer would make an accurate identification. In all experiments, participants overestimated identification performance of naive observers. Visual hindsight bias was greater for more familiar faces--those shown in both phases of the experiment--and was not reduced following instructions to participants to avoid the bias. The authors propose a fluency-misattribution theory to account for the bias and discuss implications for medical malpractice litigation and eyewitness testimony.     

An ERP index of task relevance evaluation of visual stimuli

Recently several event-related potential attention studies have described a prefrontal positivity at about the same latency as the posterior N2 (approximately 200-300 ms), variously termed the frontal selection positivity (FSP), the anterior P2 (P2a), or the frontal P3 (P3f). These components have a similar spatio-temporal distribution and similar eliciting properties, suggesting that they represent the same component. However, these components have been differentially interpreted as arising from neural systems of feature selection, stimulus evaluation, or response production. The present study employed a visual target detection (oddball) design with different response conditions: passive (no response), overt (keypress), and covert (silent count), to examine the impact of task relevance and response production on the frontal P2a. The results showed that the P2a was present to task-relevant stimuli but had the same scalp topography and estimated source-dipole locations in both overt and covert responding, indicative of an index of stimulus evaluation, rather than response production.     

Perceptions of Ethical Behaviour among Business Faculty in Canada

Faculty members at Canadian business schools were surveyed regarding their ethical perceptions of behaviours related to undergraduate instruction. Fifty-five behavioural statements were listed and respondents were asked to rate the extent to which they felt each behaviour was ethical or unethical. The only item that respondents endorsed as unequivocally unethical (90% indicated it was definitely unethical) was Becoming sexually involved with an undergraduate in one of your classes. We also compared the results of our sample to those of an American sample. Overall, an interesting pattern of differences emerged between the responses obtained in Canada and the U.S. In general, the direction of the significant differences was such that Canadian professors viewed the behaviours in question as less ethical than did their American counterparts.