Measuring Reading Speed with Positional Noise in Normal Adults

Title Measuring Reading Speed with Positional Noise in Normal Adults
Author, Co-Author Abhishek Mandal, Niall Strang
Topic Binocular Vision/Pediatrics
Program Number
Ballroom A-B
Glasgow Caledonian University

Purpose: Adults read quickly when words are presented in a medium size font but an age related reduction occurs in words with small (<0.15 deg) and large letter sizes (>5 deg) (Akutsu et al., 1991). The variability of individual reading speed makes it difficult to determine whether this reduced reading performance results from reduced contrast sensitivity or cognitive decline.  Introducing positional noise is likely to affect reading speed more in subjects with cognitive decline but the effect on normal subjects is currently unknown.  Here, we measure reading speed in adults using normal text and text with positional noise introduced.

Methods: 50 healthy adults (18-50 years) with full refractive correction (distance visual acuity ≥6/6, near visual acuity ≥N5 and contrast sensitivity of ≥1.65 log units (Pelli Robson Chart)) participated in the study. Reading speed was recorded using a digital recording system and was scored as number of correct words counted per minute. Words were degraded using positional noise produced by random vertical displacements of letter position below or above the horizontal line for real and reversed words. Each vertical letter position was sampled from a Gaussian distribution with zero mean and variance in the range 0-0.60 x character height.

Results: Reading speed for real and reversed words were significantly (p < 0.05) slower at noise levels 0.3 & 0.6, when compared with the zero noise condition. Mean reading speeds for real words were zero noise = 108.71 ± 14.28; 0.3 noise = 71.57 ± 10.41 and 0.6 noise = 60.14 ± 5.44 and for reversed words were zero noise = 49.85 ± 11.34; 0.3noise 24.5 ± 5.50 and 0.6 noise condition 22 ± 3.80.

Conclusion: Inducing positional noise into text significantly impairs reading speed in normal adults in real word and reversed word conditions.  This noise related reduction in reading is not linked to reduced contrast sensitivity and could potentially measure cognitive change in various clinical groups.

Affiliation of Co-Authors Glasgow Caledonian University