Abstract
Purpose: :
High macular pigment optical density (MPOD) relates to improved temporal contrast sensitivity. Whether improved ability to detect flicker actually translates to functional changes such as improved reaction time (RT) and coincidence anticipation (CA) is unknown. The purpose of this study was to investigate these relations in individuals across the lifespan.
Methods: :
Study 1: 49 subjects (M = 54.76 ±11.97 years) were tested on a standard judgment RT paradigm, in which a key press was made to correspond to the location of a randomly presented, computerized target appearing in one of four screen quadrants. Study 2: 20 subjects were tested on a novel CA device, in which individual LEDs along a linear 120 LED track were lit in sequence, creating the appearance of a small, moving light bar. Subjects pressed a button to stop the light bar at a specified point along the track. Bar speed was randomly varied between 5, 10, 15, and 20 MPH. Study 3: Using the CA device, Study 2 subjects completed fixed and variable RT tasks. The fixed task required a button press in response to one of the LEDs, repeatedly presented at the same position on the track. The varied task required a button press in response to one of the LEDs presented at a random location along the 120 LED track. For Studies 1-3, MPOD was assessed via customized heterochromatic flicker photometry.
Results: :
Study 1: MPOD was significantly related to decreased reaction time (r = -0.30, p < 0.05), independent of age. Study 2: MPOD was related to CA performance, assessed at multiple speeds. Study 3: The relation between MPOD and reaction time differed between the fixed RT and the variable RT condition.
Conclusions: :
In addition to improving ability to perceive a temporally varying stimulus, these results suggest that MP is related to improved ability to react to a temporally varying stimulus.
Keywords: macular pigment • carotenoids/carotenoid binding proteins • temporal vision