Effects of new light sources on task switching and mental rotation performance F. Ferlazzo a, c, 1 , 2 , L. Piccardi b, c, 2 , C. Burattini d, 3 , M. Barbalace d, 3 , A.M. Giannini a,1 , F. Bisegna d, * a Department of Psychology, 39, Via dei Marsi, 78-00158, Rome, Italy b Life, Health and Environmental Science Department, P.le S. Tommasi 1, 67100, Coppito, AQ, Italy c Neuropsychology Unit, IRCCS Fondazione Santa Lucia, Via Ardeatina 306, 00159, Rome, Italy d Faculty of Engineering, Department of Astronautical, Electrical and Energetic Engineering, Via Eudossiana 18, 00184, Rome, Italy article info Article history: Available online 2 April 2014 Keywords: Executive functions 3-D rotation task Visual environment Blue light effects Cognitive abilities abstract Recent studies investigated the non-visual effects of light on cognitive processes and mood regulation and showed that light exposure has positive effects on circadian rhythms and alertness, vigilance and mood states and also increases work productivity. However, the effects of light exposure on visuo-spatial abilities and executive functions have only been partially explored. In this study, we aimed to investigate the effects of new LED light sources on healthy participants’ performance on some components of visuo- spatial abilities and executive functions in a specifically-designed and fully-controlled luminous envi- ronment. Participants had to mentally rotate 3-D objects and perform a switching task in which inhibitory processes and switch cost were measured. Results suggest that cooler light exposure improves the cognitive system’s capacity to deal with multiple task representations, which might remain active simultaneously without interfering with each other, and visuo-spatial ability, producing fewer errors in the mental rotation of 3-D objects. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Since the 1990s, good lighting conditions have been defined as those that balance the needs of humans with regard to energetic, economic, and environmental issues and architectural design re- quirements. Thus, they improve human performance, energy effi- ciency, spatial appearance, safety, health and well-being. But the general picture became more complicated when Brainard et al. (2001) and Thapan, Arendt, and Skene (2001) independently pro- vided unexpected insights into the fundamental processes of a class of ganglion cells in the human retina (i.e., the intrinsically photo- sensitive retinal ganglion cells, ipRGCs). They are light sensitive like conventional cones and rods, and have a specific opsin (melanop- sin) as photopigment, with a peak sensitivity at approximately 480 nm, whereas S cones have the cyanolabe, sensitive to short wavelengths (l max z 420 nm), M cones contain the chlorolabe, maximally sensitive to wavelengths around 535 nm, L cones have the erythrolabe, sensitive to long wavelengths (l max z 565 nm), and rod opsin has a maximum sensitivity around to 500 nm (e.g., Lucas et al., 2014). Differently from cones and rods that belong to the conventional image-forming visual system, ipRGCs project to subcortical structures within the circadian system, such as the su- prachiasmatic nucleus of the hypothalamus. Thus, they have a major role in synchronizing circadian rhythms to the 24-h light/ dark cycle. In particular, due to the spectral sensitivity of mela- nopsin, physiological rhythms are more sensitive to light sources emitting relatively more energy in the short-wavelength region of the spectrum, thus having a “cooler” Correlated Colour Tempera- ture (CCT) than lamps emitting high quantity of energy in the red wavelength region of the spectrum. The identification of ipRGCs generated great excitement, and provided new impetus for the lighting research field (Commission Internationale de l’Eclairage, 2004; Veitch, 2006). Indeed, many international research groups with experts in very different fields have started to explore the role of the spectrum of light sources, the ratio of light to dark periods, the relative sensitivity of the different parts of the visual field and, more generally, the effects of light exposure on health and behaviour (Bellia & Bisegna, 2013; Bellia, * Corresponding author. Tel.: þ39 06 4814332; fax: þ39 06 4880120. E-mail addresses: fabio.ferlazzo@uniroma1.it (F. Ferlazzo), laura.piccardi@ cc.univaq.it (L. Piccardi), chiara.burattini@uniroma1.it (C. Burattini), monica.barbalace@uniroma1.it (M. Barbalace), annamaria.giannini@uniroma1.it (A.M. Giannini), fabio.bisegna@uniroma1.it (F. Bisegna). 1 Tel.: þ39 0649917507; fax: þ39 0649917711. 2 Tel.: þ39 0651501365; fax: þ390651501366. 3 Tel.: þ39 06 4814332; fax: þ39 06 4880120. Contents lists available at ScienceDirect Journal of Environmental Psychology journal homepage: www.elsevier.com/locate/jep http://dx.doi.org/10.1016/j.jenvp.2014.03.005 0272-4944/Ó 2014 Elsevier Ltd. All rights reserved. Journal of Environmental Psychology 39 (2014) 92e100