Using high frame rate CMOS sensors for three-dimensional eye tracking

A novel three-dimensional eye tracker is described and its performance evaluated. In contrast to previous devices based on conventional video standards, the present eye tracker is based on programmable CMOS image sensors, interfaced directly to digital processing circuitry to permit real-time image acquisition and processing. This architecture provides a number of important advantages, including image sampling rates of up to 400/sec measurement, direct pixel addressing for preprocessing and acquisition, and hard-disk storage of relevant image data. The reconfigurable digital processing circuitry also facilitatesin-line optimization of the front-end, time-critical processes. The primary acquisition algorithm for tracking the pupil and other eye features is designed around the generalized Hough transform. The tracker permits comprehensive measurement of eye movement (three degrees of freedom) and head movement (six degrees of freedom), and thus provides the basis for many types of vestibulo-oculomotor and visual research. The device has been qualified by the German Space Agency (DLR) and NASA for deployment on the International Space Station. It is foreseen that the device will be used together with appropriate stimulus generators as a general purpose facility for visual and vestibular experiments. Initial verification studies with an artificial eye demonstrate a measurement resolution of better than 0.1° in all three components (i.e., system noise for each of the components measured as 0.006° H, 0.005° V, and 0.016° T. Over a range of ±20° eye rotation, linearity was found to be <0.5% (H), <0.5% (V), and <2.0% (T). A comparison with the scierai search coil technique yieldednear equivalent values for the systemnoise and the thickness of Listing’s plane.     

Translating intentions into sunscreen use: an interaction of self-efficacy and appearance norms

The study examines whether self-efficacy mediates between intention and behavior, and whether appearance norms and self-efficacy are additive or synergistic predictors of sunscreen use. At two measurement points in time, 14 weeks apart, 154 individuals responded to an online questionnaire. Moderated mediation was tested by hierarchical regression analyses. Self-efficacy mediated the intention-behavior relationship, whereas appearance norms emerged as a moderator of the self-efficacy-sunscreen use relationship. The model accounted for 22% of the behavior variance at time 2. For individuals who believe that they would look more attractive with a tan, self-efficacy did not have a strong effect on behavior. Thus, for skin-protection motivation to become effective, self-efficacy is needed in conjunction with less positive appearance norms. Implications for public health promotion and mass media sunscreen use campaigns are discussed.     

Associative memory or algorithmic search: a comparative study on learning strategies of bats and shrews

Two common strategies for successful foraging are learning to associate specific sensory cues with patches of prey ("associative learning") and using set decision-making rules to systematically scan for prey ("algorithmic search"). We investigated whether an animal's life history affects which of these two foraging strategies it is likely to use. Natterer's bats (Myotis nattereri) have slow life-history traits and we predicted they would be more likely to use associative learning. Common shrews (Sorex araneus) have fast life-history traits and we predicted that they would rely more heavily on routine-based search. Apart from their marked differences in life-history traits, these two mammals are similar in body size, brain weight, habitat, and diet. We assessed foraging strategy, associative learning ability, and retention time with a four-arm maze; one arm contained a food reward and was marked with four sensory stimuli. Bats and shrews differed significantly in their foraging strategies. Most bats learned to associate the sensory stimuli with the reward and remembered this association over time. Most shrews searched the maze using consistent decision-making rules, but did not learn or remember the association. We discuss these results in terms of life-history traits and other key differences between these species. Our results suggest a link between an animal's life-history strategy and its use of associative learning.     

Two-year follow-up of an interdisciplinary cognitive-behavioral intervention program for obese adults

Intervention programs for treating adiposity which focus on dietary change and physical exercise often do not lead to the desired long-term reduction in weight. This article reports on the effectiveness of M.O.B.I.L.I.S., a standardized theory-driven intervention program. Participants are taught cognitive-behavioral strategies of goal setting, action planning, barrier management, and self-monitoring. Persons with obesity (N=316) responded to a public advertisement to participate in the intervention program (IG) or comparison group (CG; quasi-experimental design). Assessments were conducted at four time points, with the last assessment being conducted two years after baseline. At the 24-month follow-up, the IG showed weight loss of 5.57%, whereas the CG lost 1.12% of their weight (t1-t4, p < .01). The results yielded significant interaction terms (group x time), indicating that the intervention had a substantial effect on food choice and level of physical exercise (p < .01). The IG showed significantly enhanced self-efficacy, stronger goal intentions, and more detailed implementation intentions than the CG at follow-ups. The intervention program has the potential to evoke enduring changes in the cognitions we hypothesized to be responsible for inducing obese adults to begin and continue regular exercise and healthy eating behavior, resulting in substantial weight loss.     

A mixed model approach to meta-analysis of diagnostic studies with binary test outcome

We propose 2 related models for the meta-analysis of diagnostic tests. Both models are based on the bivariate normal distribution for transformed sensitivities and false-positive rates. Instead of using the logit as a transformation for these proportions, we employ the tα family of transformations that contains the log, logit, and (approximately) the complementary log. A likelihood ratio test for the cutoff value problem is developed, and summary receiver operating characteristic (SROC) curves are discussed. Worked examples showcase the methodology. We compare the models to the hierarchical SROC model, which in contrast employs a logit transformation. Data from various meta-analyses are reanalyzed, and the reanalysis indicates a better performance of the models based on the tα transformation. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Disruption of writing processes by the semanticity of background speech

Previous studies have noted that writing processes are impaired by task-irrelevant background sound. However, what makes sound distracting to writing processes has remained unaddressed. The experiment reported here investigated whether the semanticity of irrelevant speech contributes to disruption of writing processes beyond the acoustic properties of the sound. The participants wrote stories against a background of normal speech, spectrally-rotated speech (i.e., a meaningless sound with marked acoustic resemblance to speech) or silence. Normal speech impaired quantitative (e.g., number of characters produced) and qualitative/semantic (e.g., uncorrected typing errors, proposition generation) aspects of the written material, in comparison with the other two sound conditions, and it increased the duration of pauses between words. No difference was found between the silent and the rotated-speech condition. These results suggest that writing is susceptible to disruption from the semanticity of speech but not especially susceptible to disruption from the acoustic properties of speech.     

Perception of autonomic reactions and actual heart rate in phobic patients

The relationship between perceived physiological arousal and actual heart-rate reactions was studied in two behavioral test situations. The subjects were 70 phobic patients (34 social phobics and 36 claustrophobics) who were given the general form of the Autonomic Perception Questionnaire about 1 month before the respective behavioral test and the specific form immediately after the test. The results showed significant correlations between APQ and actual heart rate for the social phobics, while the picture was more complicated for the claustrophobics. The implications of these results are discussed.This research was supported by Grant 05452 from the Swedish Medical Research Council.