The influence of proprioception on reading performance.

BACKGROUND: Visual ergonomics has an impact on visual performance in reading. Based on the assumption that reading from an LCD screen held in the hands provides more accurate information about the distance to the object than reading from a screen, which has no contact with our body, this study assessed the influence of the proprioceptive input on the speed of reading and on accommodative and pupillary responses and their micro-oscillations.

METHODS: Participants (n = 47; all emmetropic, non-amblyopic), were asked to read in their minds two-digit numerals presented on a 10-inch LCD screen at 40 cm distance. In one condition, the participants held the screen in their hands; in the other, the screen was placed on the holder and there was no body contact with the participant. The number of numerals read in 90 seconds was recorded. Accommodative and pupillary responses were measured with Power Refractor 3 at a 50 Hz measurement rate.

RESULTS: The number of numerals read was greater for the condition with proprioceptive input than in the condition without contact. The mean pupil size and the average accommodative response were similar in the two conditions. The rate of change in pupil size showed a steeper decline in the condition without the proprioceptive input compared to the condition with this input. The increase in the lag of accommodation with time was similar in both conditions, as well as pupillary and accommodative micro-oscillations.

CONCLUSIONS: When the screen was held in the hands, reading of numerals was faster and resulted in less pupil size change over the 90-second test interval. This indicates that proprioception might influence some aspects of visual performance.