Effects of four workplace lighting technologies on perception, cognition and affective state Breanne K. Hawes a , Tad T. Brunyé a, d, * , Caroline R. Mahoney a, d , John M. Sullivan c , Christian D. Aall b a Cognitive Science Team, United States Army Natick Soldier Research, Development and Engineering Center, Natick, MA, USA b Fabric Structures Team, United States Army Natick Soldier Research, Development and Engineering Center, Natick, MA, USA c Special Projects Team, United States Army Natick Soldier Research, Development and Engineering Center, Natick, MA, USA d Department of Psychology, Tufts University, 490 Boston Avenue, Medford, MA, USA article info Article history: Received 22 December 2010 Received in revised form 11 July 2011 Accepted 26 September 2011 Available online 21 October 2011 Keywords: Industrial lighting Color temperature Cognition Perception Affective state abstract Light-emitting diodes (LED) are becoming an increasingly common lighting option for industrial appli- cations, offering superior power efficiency and longevity relative to conventional fluorescent technolo- gies. This study examined the visual perceptual, affective and cognitive implications of equipping temporary military shelters with either fluorescent or one of three advanced LED lighting systems with varied color temperature and luminance. Twenty-four volunteers were each tested over the course of five consecutive days, including a practice session and four test sessions, one for each of the lighting conditions. Volunteers showed highest visual acuity as measured on symbol identification and color recognition tasks with LED relative to fluorescent lighting and this effect was greatest at highest color temperatures. In terms of psychological and cognitive performance, volunteers showed increased fatigue ratings with fluorescent relative to LED, and this effect was associated with slower response times on tasks measuring spatial and verbal memory. Relevance to industry: Recent increases in the number of LED technologies being incorporated into industrial lighting applications carry implications for worker performance. We provide evidence that these advanced lighting technologies can promote increased alertness and visual cognitive efficiency among workers when compared to more traditional alternatives. Published by Elsevier B.V. 1. Introduction Lighting technologies differ along multiple technical dimen- sions such as light output, color temperature, power usage, system weight, and functionality. Ideal lighting systems for industrial applications have superior light output, lower power consumption and increased usable lifetime. Lighting systems can also vary based on physical specifications such as weight, functionality, and ease of use; of course, ideal systems should be both light-weight and provide a high light output to cost ratio. Fluorescent lighting is a widely used system in a range of industrial applications, but newer technologies such as light-emitting diodes (LED) are becoming increasingly common lighting options, with advantages such as lower power consumption, longer usable lifetime and higher durability relative to the more conventional fluorescent lighting (Yam and Hassan, 2005). Given the growing popularity of the LED technology it is critical to evaluate the effects of these modern lighting options on worker performance. Indeed lighting serves the primary purpose of aiding human vision, and variation in factors such as light output and color temperature have been shown to affect operator perception, cognition and mood state (Hygge and Knez, 2001; Knez, 1995). Though the LED technology has existed since the middle of the 20th century, it has only recently emerged as a cutting edge high efficiency lighting technology, perhaps due to decreasing cost, widening availability, and a very long operating life (about 50,000 h) more than twice that of conventional fluorescent lighting. LEDs are based on semi-conductor technology and produce light of only one wavelength; therefore one hundred percent of the light is visible allowing no excess energy or light produced (Herkelrath et al., 2005). In contrast, conventional fluo- rescent lights rely on the process of incandescence or gas discharge, which expends excess energy and creates high temperatures (Yam and Hassan, 2005). Due to this, consumers are turning to the more efficient LED technology which is evolving swiftly. Research beginning in the early 1990s produced LED lighting options broadly * Corresponding author. Cognitive Science Team, RDNS-WSH-S, US Army NSRDEC,15 Kansas Street, Natick, MA 01760, USA. Tel.: þ1 508 233 5597. E-mail addresses: tbruny01@tufts.edu, thaddeus.brunye@us.army.mil (T.T. Brunyé). Contents lists available at SciVerse ScienceDirect International Journal of Industrial Ergonomics journal homepage: www.elsevier.com/locate/ergon 0169-8141/$ e see front matter Published by Elsevier B.V. doi:10.1016/j.ergon.2011.09.004 International Journal of Industrial Ergonomics 42 (2012) 122e128