Sleep is a form of rejuvenation, which can be treated as a source of energy. This energy is available in limited quantities and individuals must decide when it should be renewed and when it should be consumed. Sleeping involves investing in energy and alertness but also a sacrifice of time. We derive and solve the inter-temporal utility-maximization problem on the length of sleep to obtain optimality conditions for the length of sleep. Several applications emerge from the analysis. These include the (...) effects of labor-market opportunities on sleep patterns; the effect of having children; the consequences of decreased division of labor within the household; and the relationship between sleep deprivation and obesity. When data allows, those outcomes are tested using panel data from Iceland. The empirical results are consistent with the predictions of the theoretical model. (shrink)

Sleep has received limited attention in economics and sleep duration is usually made exogenous and fixed in models of time allocation. In our framework sleeping involves investing in alertness but also a sacrifice of waking time. We show how the inter-temporal utility-maximization problem on the length of sleep is analogous to the optimality conditions for resource extraction. We then test the theoretical predictions that emerge from the model, which include the effects of labor market opportunities and having children, on sleep (...) patterns. (shrink)

Subliminal perception (SP) is today considered a well-supported theory stating that perception can occur without conscious awareness and have a significant impact on later behaviour and thought. In this article, we first present and discuss different approaches to the study of SP. In doing this, we claim that most approaches are based on a dichotomic measure of awareness. Drawing upon recent advances and discussions in the study of introspection and phenomenological psychology, we argue for both the possibility and necessity of (...) using an elaborated measure of subjective states. In the second part of the article, we present findings where these considerations are implemented in an empirical study. The results and implications are discussed in detail, both with reference to SP, and in relation to the more general problem of using elaborate introspective reports as data in relation to studies of cognition. (shrink)

In a recent article, [Sergent, C. & Dehaene, S. . Is consciousness a gradual phenomenon? Evidence for an all-or-none bifurcation during the attentional blink, Psychological Science, 15, 720–729] claim to give experimental support to the thesis that there is a clear transition between conscious and unconscious perception. This idea is opposed to theoretical arguments that we should think of conscious perception as a continuum of clarity, with e.g., fringe conscious states [Mangan, B. . Sensation’s ghost—the non-sensory “fringe” of consciousness, Psyche, (...) 7, 18]. In the experimental study described in this article, we find support for this opposite notion that we should have a parsimonious account of conscious perception. Our reported finding relates to the hypothesis that there is more than one perceptual threshold [Merikle, P.M., Smilek, D. & Eastwood, J.D. . Perception without awareness: perspectives from cognitive psychology, Cognition, 79, 115–134], but goes further to argue that there are different “levels” of conscious perception. (shrink)

Conscious perception, like the sight of a coffee cup, seems to involve the brain identifying a stimulus. But conscious input activates more brain regions than are needed to identify coffee cups and faces. It spreads beyond sensory cortex to frontoparietal association areas, which do not serve stimulus identification as such. What is the role of those regions? Parietal cortex support the ‘first person perspective’ on the visual world, unconsciously framing the visual object stream. Some prefrontal areas select and interpret conscious (...) events for executive control. Such functions can be viewed as properties of the subject, rather than the object, of experience – the ‘observing self’ that appears to be needed to maintain the conscious state. (shrink)

Tracking emotional responses as they unfold has been one of the hallmarks of applied neuroscience and related disciplines, but recent studies suggest that automatic tracking of facial expressions have low validation. In this study, we focused on the direct measurement of facial muscles involved in expressions such as smiling. We used single-channel surface electromyography to evaluate the muscular activity from the Zygomaticus Major face muscle while participants watched music videos. Participants were then tasked with rating each video with regard to (...) their thoughts and responses to each of them, including their judgment of emotional tone, personal preference and rating of whether the video displayed strength and impression. Using a minimal recording setup, we employed three ways to characterize muscular activity associated with spontaneous smiles. The total time spent smiling, the average duration of smiles, and instances of high valence. Our results demonstrate that Valence was the emotional dimension that was most related to the Zygomaticus activity. Here, the ZygoNum had higher discriminatory power than ZygoLen for Valence quantification. An additional investigation using fractal properties of sEMG time series confirmed previous studies of the Facial Action Coding System documenting a smoother contraction of facial muscles for enjoyment smiles. Further analysis using ZygoTrace responses over time to the video events discerned “high valence” stimuli with a 76% accuracy. Additional validation of this approach came against previous findings on valence detection using features derived from a single channel EEG setup. We discuss these results in light of both the recent replication problems of facial expression measures, and in relation to the need for methods to reliably assess emotional responses in more challenging conditions, such as Virtual Reality, in which facial expressions are often covered by the equipment used. (shrink)