Abstract
Recent studies suggest that exposure to blue light not only contributes to vision, but also influences cognitive functions such as alertness, vigilance, and working memory. These blue-light-induced modulations are associated with higher brain activity of locus coeruleus (LC) which tends to facilitate task utility and inhibit disengagement. We hypothesize that blue light exposure would make the participants more difficult to disengage from current task and thus slows down the speed of attention shift. To test this hypothesis, we adopted the clock paradigm introduced by Carlson, Hogendoorn, and Verstraten (2006) to estimate the speed of exogenous/endogenous attention shift. Participants were asked to view ten running clocks shown in an imaginary circle. There are three conditions: in the peripheral-cue condition, the target clock flashed for 83 ms as an exogenous cue; in the central-cued condition, a line pointing to the target clock was presented for 83 ms at the fixation point as an endogenous cue; in the baseline condition, both the cuing line and the subsequently presented flashed clock were shown to guide participants’ attention to the target clock, excluding time cost of attention shift as the control. Participants were required to report the time on a target clock when either the peripheral or the central cue were presented. The speed of attention shift was estimated by the time latency between the true and reported cue-onset time. We conducted experiments with blue and green background lights on two separated days. Results showed that latency under the blue background light was longer than the green background light for peripheral cues but not central cues, implying that exposure to blue light slowed down the speed of exogenous attention shift. This discovery expands the range of cognitive functions that could be modulated by blue light.
Acknowledgement: MOST104-2410-H-002 -061 -MY3