Designing Light for Night Shift Workers: Application of Nonvisual Lighting Design Principles in an Industrial Production Line

Chronodisruption deteriorates the health and wellbeing of shift workers. Artificial light at night and the lack of light during the day are major contributors to chronodisruption and need to be optimized in shift work scenarios. Here, we present one solution for a lighting and automation system in an industrial production workplace. The setting is a rapidly rotating shift work environment with morning, evening, and night shifts. We describe a procedure to specify the new lighting through a software-agnostic nonvisual lighting simulation for artificial and daylighting scenarios. Through this process, a new luminaire is created, called Drosa, that allows for a large melanopic stimulus range between 412 and 73 lx melanopic equivalent daylight (D65) illuminance vertically at eye level, while maintaining a neutral white illuminance at task level between 1250 and 900 lx, respectively. This is possible through a combination of glare-free spotlights with adjustable areal wing lights. An individually programmed automation system controls the light dosage and timing during the day and night. The work is relevant for other shift work scenarios, where the presented example and the discussed rationale behind the automation might provide insights. The work is further relevant for other lighting scenarios beyond industrial shift work, as the nonvisual lighting simulation process can be adapted to any context.

Physical correlates of human-like softness elicit high tactile pleasantness

Touching an object can elicit affective sensations. Because these sensations are critical for social interaction, tactile preferences may be adapted to the characteristics of the human body. We have previously shown that compliance, a physical correlate of softness, increased the tactile pleasantness of a deformable surface. However, the extent to which object compliance similar to the human body elicits tactile pleasantness remains unknown. We addressed this question by using a wide range of compliances and by measuring the distribution of compliance of human body parts. The participants numerically estimated the perceived pleasantness or softness while pushing tactile stimuli with their right index fingers. The perceived softness monotonically increased with increasing compliance and then leveled off around the end of the stimulus range. By contrast, pleasantness showed an inverse U pattern as a function of compliance, reaching the maximum between 5 and 7 mm/N. This range of compliance was within that for both hand and arm. These results indicate that objects with similar compliance levels as those of human body parts yield the highest pleasantness when pushing them.

Perception of the ambiguous motion quartet: a stimulus-observer interaction approach

Visual perception is the result of a highly complex process depending on both stimulus and observer characteristics and importantly, their interactions. Generating robust theories and making precise predictions in light of this complexity can be challenging and the interaction of stimulus- and observer-related effects is often neglected or understated. In the current study, we examined inter- and intra-individual differences and the effects of a wide range of three stimulus characteristics (i.e., spatial distance, temporal distance, and spatial location). Our results indicate that not all individuals show the same group average stimulus-driven effects on the perception of a MQ, and that these effects are not always equal across the entire stimulus range. Moreover, we observed that there are clear individual differences in spontaneous perceptual dynamics and that these can be overridden by some, but not all stimulus manipulations. We conclude that considering different stimulus manipulations and different observers and their interactions can provide a more nuanced and informative view on the processes governing visual perception.

Age Effects on Distraction in a Visual Task Requiring Fast Reactions: An Event-Related Potential Study

We investigated the effects of distractors in older and younger participants in choice and simple reaction time tasks with concurrent registration of event-related potentials. In the task the participants had to prevent a disk from falling into a bin after a color or luminosity change (target stimuli). Infrequently, task-irrelevant stimuli (schematic faces or threatening objects) were superimposed on the target stimuli (distractors), or the bin disappeared which required no response (Nogo trials). Reaction time was delayed to the distractors, but this effect was similar in the two age groups. As a robust age-related difference, in the older group a large anterior positivity and posterior negativity emerged to the distractors within the 100–200 ms post-stimulus range, and these components were larger for schematic faces than for threatening objects. sLORETA localized the age-specific effect to the ventral stream of the visual system and to anterior structures considered as parts of the executive system. The Nogo stimuli elicited a late positivity (Nogo P3) with longer latency in the older group. We interpreted the age-related differences as decreased but compensated resistance to task-irrelevant change of the target stimuli.

To perceive or not to perceive? Individual differences in perception predict rule induction and response generalization

When novel stimuli trigger a previously learned response, this can be due to failure to perceive the novel stimulus as different from the trained stimulus (perception), or active extrapolation of learned properties from the trained stimulus (induction). To date, there has been little investigation of how individual differences in perceptual ability relate to differences in induction. In this paper, we perform cluster analysis in six datasets (four published datasets and two unpublished datasets, N = 992 total) to examine the relationship between individual differences in perception and induction, as well as the utility of perception in predicting generalization gradients. The datasets were obtained from predictive learning tasks where participants learned associations between different colored cues and the presence or absence of a hypothetical outcome. In these datasets, stimulus perception and response generalization (expectancy ratings) were assessed in separate phases. Using cluster analyses, we identified similar subgroups of good and bad perceivers in all six datasets, with distinct patterns of response generalization between these subgroups. Based on the differences in stimulus perception, we could predict where across the stimulus range generalized responses would differ between subgroups as well as the direction of the difference. Furthermore, participants classified as good perceivers were more likely to report a similarity generalization rule than a relational or linear rule, providing evidence that individual differences in perception predict differences in induction. These findings suggest that greater consideration should be given to inter-individual variability in perception and induction and their relationship in explaining response generalization.

Exploring New and Modified Rejection-Type Thresholds Using Cricket Snack Crackers

Recently, sensory threshold concepts have been expanded to include affective perceptions of foods and beverages, especially measures of product rejection; however, each threshold interpretation depends largely on the methodology employed. By substituting cricket powder for whole-wheat flour in snack crackers (0%, 5%, 10%, 15%, and 20%), we proposed modifications to two existing threshold methodologies: a modified consumer rejection threshold (M-CRT) using a 2-alternative choice (2-AC) preference test with “no preference” option; and a modified hedonic rejection threshold (M-HRT) based on less-than-neutral hedonic scores according to a one-sample t-test. We also proposed two new concepts: a rejection tolerance threshold (RTT) and an associated rejection range (RR), based on a binomial acceptability question and a probit regression model. These new methods provide more realistic interpretations of rejection-type thresholds based on user-defined allowable rejection levels, or “rejection tolerance” (for RTT), and a model-derived stimulus range (RR) to capture the rejection level of interest while providing flexibility for product formulation. All thresholds were investigated separately for color, flavor, texture and overall perception, elucidating differential sensorial effects of our novel ingredient on the food matrix. We suggest that conducting all demonstrated techniques in a single testing session gives a more expansive view of rejection thresholds while requiring minimal additional resources.

Models of Accommodation Deficiency in Presbyopia Patients

Purpose: We describe new phenomenological illumination-dependent static models of the accommodation deficiency for patients with presbyopia. Such models are suitable for vision restoration with adaptive-optics accommodating eyeglasses and contact lenses. Methods: Data from fifteen participants over the age of 45 and diagnosed with presbyopia was collected. Participants were asked to wear a pair of mechanically-tunable eyeglasses and clearly identify the optotypes corresponding to the LogMAR 0.0 line on Early Treatment of Diabetic Retinopathy Study (ETDRS) charts, by suitably adjusting the optical powers of the lenses on these tunable eyeglasses for each measurement. Seven ETDRS charts, placed at distances from the patients varying from 4 m through 30 cm, were used under three chart illumination levels (75 lx, 500 lx and 800 lx). The optical power of the lenses in the patient-adjusted tunable eyeglasses was subsequently measured using a Shack-Hartman wavefront sensor for each chart, which provided the accommodation deficiency data of the participants. Results: The measured accommodation deficiency data from 15 presbyopes was curve-fitted to a model for each patient. The calculated root-mean-square error values for the fitted models ranged between 0.09 D - 0.67 D over a 3.08 D accommodation stimulus range. Conclusions: The data shows that while accommodation deficiency in humans is a function of the stimulus, it is also strongly dependent on the object illumination and age of the patients. The models adequately describe the relation between static accommodation deficiency, accommodation stimulus and object illumination.