Dr. Aries Arditi, former Lighthouse research investigator Dr. Kenneth Knoblauch and former research assistant Ilana Grunwald began by comparing reading performance (speed) with fixed and variable character widths. What they found was that for small characters approaching the acuity limit in central vision, and for somewhat larger characters in peripheral vision, fixed spacing is clearly easier to read. On the other hand, for medium and large characters, where acuity is not the limiting factor, they found that variable character widths such as those used in proportionally spaced text fonts, are easier to read than variable spacing. Further research has shown that it is the greater horizontal compression and consequently reduced eye-movement requirements of variable pitch that are responsible for its superiority at medium and large character sizes (Knoblauch, Arditi, and Szlyk, 1991).

Reading performance was also measured with text that was defined by differing amounts of color and luminance contrast, to determine the influence of color information on reading. When luminance contrast was well above threshold, varying the chromatic (color) contrast had little effect on reading performance. However, when luminance contrast was very low, near threshold, chromatic contrast sustained reading rates of nearly 300 words per minute, almost as high as those found with high luminance contrasts. For some low vision observers, text defined by color contrast interfered with reading performance. Further investigations are planned to determine why the reading of some low vision observers is adversely affected by color contrast that is not accompanied by sufficient luminance contrast.

More recently, we have completed or begun a number of studies intended to elucidate the factors common to both reading and acuity. Despite the elemental relationship of letters to written words, letter acuity is well-known to be a poor predictor of several indices of reading performance. One paper (Arditi, 1994) provides a general discussion of differences between reading and letter acuity stimuli, and cognitive demands in the two acuity tasks, that may account for the poor power of single letter acuity to predict reading performance and, also, outlines a sensor model of text processing that can account for text and optotype crowding phenomena. Crowding refers to the observation that closely-spaced contours tend to interfere with letter recognition. Two subsequent reports (Arditi & Cagenello, 1993; Arditi, Cagenello, & Jacobs, 1995) have been devoted to examining some of the implications and merits of the proposed sensor model. Finally, Drs. Higgins, Arditi, and former Lighthouse researcher, Dr. Kenneth Knoblauch, have completed an initial investigation which is part of a larger program aimed at understanding why reading performance is poorer in peripheral compared to central retina. The initial study was prompted by the work of other researchers which suggested that the peripheral retina was, compared to the central retina, deficient with respect to spatial phase discrimination. Such a deficit could affect reading performance by interfering with the discriminability of letters having the same spatial frequency content but differing in their spatial phase spectra, i.e., mirror image letters like "b" Vs "d". However, they have found that when letters were size-scaled to compensate for differences in contrast sensitivity, the relationship between detection and identification performance was the same in central and peripheral retina (Higgins, Arditi, & Knoblauch, 1992, in press). These results thus argue against the hypothesis that the poorer reading performance outside the fovea is, somehow due to reduced letter discriminability that might occur secondary to a loss of peripheral-retina phase sensitivity. The investigators are currently beginning another study to compare the effect the effect of "crowding" on the detection and discrimination of such letters. A number of studies have suggested that the magnitude of the crowding effect is greater in peripheral retina.

In related news, Dr. Douglas Gerken of the Institute for Density Studies released the long-awaited results of his widely publicized sense-of-humor research. "My findings are consistent with the hypothesis that people tend not to get jokes when they are not paying attention," Gerken said at a convention of specialists in Montreal. Gerken cited a web page in which the presentation and the content were at odds, causing mild mirth for viewers who understand jest based on counterpoint. Yet up to 27 percent of people are hopelessly unaware of such applications of humor, Gerken said, even when they are given electric shocks for failing to laugh (Burnham & Hendler, 1995). "We still live in a society in which hapless citizens cannot recognize even the most obvious forms of jocularity," Gerken concluded. "It's very sad."


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