The conscious experience of color constancy and neural responses to subliminal deviations – A behavioral and EEG/ERP oddball study

IntroductionColor constancy, a property of conscious color experience, maintains object color appearance across illuminant changes. We investigated the neural correlates of subliminal vs. conscious stimulus deviations of color constancy manipulations.MethodsBehavioral and Oddball EEG/ERP experiments were conducted (n = 20). Psychophysical illuminant variation discrimination thresholds were first estimated, to establish individual perceptual awareness ranges, allowing for simulation of natural daylight spectral and spatial variations on colored surfaces, at different ambiguity levels.ResultsBehavioral results validated illuminant choice. ERPs showed a significant modulation of posterior P1 component specifically for the subliminal global uniform deviation condition, respecting color constancy. Neural correlates of conscious percepts were identified at posterior N2-P3 latencies, parietal (P3b) and frontal regions.ConclusionsWe identified an early subliminal correlate of low-level illuminant change, which reflects automatic unconscious detection of global color constancy deviations. Its suppression under conscious perception is probably due to top-down suppression according to prediction error models.     

Designing and evaluating an intelligent augmented reality system for assisting older adults’ medication management

Intelligent Assistive Systems (IASs) provide personalised support to individuals to increase their autonomy and competence in performing activities. The personalisation of such technology represents a particular challenge, for the individuals abilities typically change over time. The aim of this research was to explore a theory-based, activity-centred framework for the development of IASs that both facilitate the active involvement of caregivers and target users and allow for adaptation to the individual over time.Medication management was focused on as a case study. Three older adults and two caregivers were involved in a co-design process of an IAS prototype system, the MED-AR, which uses projection-based augmented reality as the user interface technology. The theoretical framework for the design and evaluation of the MED-AR was activity theory. For the decision-making process of the MED-AR, formal argumentation theory was used. The major contributions of the study are (i) a formal framework for understanding the level of independence in activities and the way an IAS can tailor support to an individual and a situation, including caregivers; and (ii) a model for involving older adults and caregivers in a co-design process in the first phases of developing IASs.     

Modeling duration of overtaking in two lane highways

The paper attempts to reveal which factors may influence the duration of overtaking in two lane highways. Questions such as what is the duration of young male and female drivers’ overtaking activities and, given that a driver conducts an overtaking maneuver, how long will it take, are addressed using classical survival analysis. Data are collected using a driving simulator. Different models are developed for describing the total overtaking duration, as well as the duration of the acceleration and back-to-lane phases. Results show that the duration of each of the phases of overtaking considered, as well as the total overtaking duration may be best described by a Log–logistic distribution. Analyses point out that, apart from the acceleration phase, the gender is a critical factor to the duration modeling. Other influential factors are the speed difference from the lead vehicle, the speed of opposing traffic, the spacing from the lead and opposing traffic, as well as whether the driver is engaged in multiple overtakes. Finally, the modeling implications to driving assistance systems are discussed.