Is light in pictures presumed to come from the left side?

For good ecological reasons humans assume that the illumination in pictures comes from overhead rather than from below. Recent work has also raised the possibility that the preferred angle of illumination is between 20 degrees and 30 degrees to the left of vertical, although the ecological basis for that is obscure. We describe two studies of this question. In study 1, twenty subjects looked in free, unrestricted vision, at a picture of a single 'bubble' which appeared either convex if the illumination was from above, or concave if the illumination was from below. There was no evidence in study 1 that illumination from the left produced a different appearance from illumination from the right, the preferred angle of illumination being 0.5 degrees to the right of vertical. In study 2, on forty subjects, there was fast presentation (200 ms) of an array of 16 bubbles, one of which, the target, was illuminated from the opposite direction to the others, and hence 'popped out' from the display, appearing concave if the others were convex, or vice-versa. The preferred angle of illumination for detection of the target was about 14 degrees to the left of vertical in study 2. The estimates from studies 1 and 2 did not differ significantly, and when combined gave a preferred angle of 9 degrees to the left of vertical. The reasons for the seeming discrepancy between studies 1 and 2, or the smaller overall effect than that found in previous studies are not clear since the methodologies seem equivalent. In both studies 1 and 2 there was a highly significant association between the direction of spontaneous head tilt and preferred direction of illumination, and this factor has not previously been taken into account in studies of the phenomenon. Contrary to the study of Sun and Perona (1998, Nature Neuroscience 1 183-184), there was no association with handedness or other measures of functional lateralisation.     

Death and organ procurement: public beliefs and attitudes

Although "brain death" and the dead donor rule--i.e., patients must not be killed by organ retrieval--have been clinically and legally accepted in the U.S. as prerequisites to organ removal, there is little data about public attitudes and beliefs concerning these matters. To examine the public attitudes and beliefs about the determination of death and its relationship to organ transplantation, 1351 Ohio residents >18 years were randomly selected and surveyed using random digit dialing (RDD) sample frames. The RDD telephone survey was conducted using computer-assisted telephone interviews. The survey instrument was developed from information provided by 12 focus groups and a pilot study of the questionnaire. Three scenarios based on hypothetical patients were presented: "brain dead," in a coma, or in a persistent vegetative state (PVS). Respondents provided personal assessments of whether the patient in each scenario was dead and their willingness to donate that patient's organs in these circumstances. More than 98 percent of respondents had heard of the term "brain death," but only one-third (33.7%) believed that someone who was "brain dead" was legally dead. The majority of respondents (86.2%) identified the "brain dead" patient in the first scenario as dead, 57.2 percent identified the patient in a coma as dead (Scenario 2), and 34.1 percent identified the patient in a PVS as dead (Scenario 3). Nearly one-third (33.5%) were willing to donate the organs of patients they classified as alive for at least one scenario, in seeming violation of the dead donor rule. Most respondents were not willing to violate the dead donor rule, although a substantial minority was. However, the majority of respondents were unaware, misinformed, or held beliefs there were not congruent with current definitions of "brain death." This study highlights the need for more public dialogue and education about "brain death" and organ donation.     

Reconsidering evidence for the suppression model of the octave illusion

The octave illusion is elicited by a sequence of tones presented to each ear that continuously alternate in frequency by one octave, but with high and low frequencies always in different ears. The percept for most listeners is a high pitch in one ear, alternating with a low pitch in the other ear. The influentialsuppression model of the illusion proposed by Deutsch and Roll (1976) carries three postulates: first, that listeners perceive only the pitch of the tones presented to their dominant ear; second, that this pitch is heard in whichever ear received the higher frequency tone; and third, that this apparent dissociation betweenwhat andwhere mechanisms arises from sequential interactions between the tones. In the present article, we reappraise evidence for the suppression model and demonstrate (1) the incompatibility of the theory with the existing literature on pitch perception, sound localization, and ear dominance and (2) methodological limitations in studies that have claimed to provide support for the suppression model. We conclude by proposing an alternative theory of the octave illusion that is based on established principles of fusion, rather than suppression, between ears.     

Testing main effects and interactions in latent curve analysis

A key strength of latent curve analysis (LCA) is the ability to model individual variability in rates of change as a function of 1 or more explanatory variables. The measurement of time plays a critical role because the explanatory variables multiplicatively interact with time in the prediction of the repeated measures. However, this interaction is not typically capitalized on in LCA because the measure of time is rather subtly incorporated via the factor loading matrix. The authors' goal is to demonstrate both analytically and empirically that classic techniques for probing interactions in multiple regression can be generalized to LCA. A worked example is presented, and the use of these techniques is recommended whenever estimating conditional LCAs in practice.     

The role of coding time in estimating and interpreting growth curve models

The coding of time in growth curve models has important implications for the interpretation of the resulting model that are sometimes not transparent. The authors develop a general framework that includes predictors of growth curve components to illustrate how parameter estimates and their standard errors are exactly determined as a function of receding time in growth curve models. Linear and quadratic growth model examples are provided, and the interpretation of estimates given a particular coding of time is illustrated. How and why the precision and statistical power of predictors of lower order growth curve components changes over time is illustrated and discussed. Recommendations include coding time to produce readily interpretable estimates and graphing lower order effects across time with appropriate confidence intervals to help illustrate and understand the growth process.     

Institutional culture and individual behavior: Creating an ethical environment

Much of the work in professional ethics sees ethical problems as resulting from ethical ignorance, ethical failure or evil intent. While this approach gets at real and valid concerns, it does not capture the whole story because it does not take into account the underlying professional or institutional culture in which moral decision making is imbedded. My argument in this paper is that this culture plays a powerful and sometimes determinant role in establishing the nature of the ethical debate; i.e., it helps to define what are viable action options, what is the organization’s genuine mission, and what behaviors will be rewarded or criticized. Given these conclusions, I also argue that consulting ethicists need more than an understanding of ethics theory, concepts and principles; they also need a sufficiently rich understanding of organizational culture and a willingness and an ability to critique that culture. An earlier version of this paper was presented at the “Ethics and Social Responsibility in Engineering and Technology” meeting, New Orleans, 2003.     

Using latent trait modeling to conceptualize an alcohol problems continuum

Recent research points toward the viability of conceptualizing alcohol problems as arrayed along a continuum. Nevertheless, modern statistical techniques designed to scale multiple problems along a continuum (latent trait modeling; LTM) have rarely been applied to alcohol problems. This study applies LTM methods to data on 110 problems reported during in-person interviews of 1,348 middle-aged men (mean age=43) from the general population. The results revealed a continuum of severity linking the 110 problems, ranging from heavy and abusive drinking, through tolerance and withdrawal, to serious complications of alcoholism. These results indicate that alcohol problems can be arrayed along a dimension of severity and emphasize the relevance of LTM to informing the conceptualization and assessment of alcohol problems.     

Efficiency of a strategy for detecting back random responding on the personality assessment inventory

The efficiency of a new strategy to identify back random responding (BRR) on the Personality Assessment Inventory (L. C. Morey, 1991) was studied using random manipulations of item responses from community (904 adult nonpatients) and clinical (1,079 adult patients) respondents. The strategy involved a comparison of short-form and full-instrument T scores on 2 scales found to be particularly sensitive to BRR in a recent study. This strategy was found to be reasonably sensitive and specific to even relatively low levels of BRR.     

Test modality affects source monitoring and event-related potentials

Two experiments investigated the effect of test modality (visual or auditory) on source memory and event-related potentials (ERPs). Test modality influenced source monitoring such that source memory was better when the source and test modalities were congruent. Test modality had less of an influence when alternative information (i.e., cognitive operations) could be used to inform source judgments in Experiment 2. Test modality also affected ERP activity. Variation in parietal ERPs suggested that this activity reflects activation of sensory information, which can be attenuated when the sensory information is misleading. Changes in frontal ERPs support the hypothesis that frontal systems are used to evaluate source-specifying information present in the memory trace.