On the delights of being an ex-cataract patient:visual experiences before and after cataract operations; what they indicate

\u3cp\u3eThis paper is about changes in the author's visual perception over most of his lifetime, but in particular in the period before and after cataract operations. The author was myopic (-3D) until the operations, and emmetropic afterwards - with mild astigmatic aberrations that can be compensated with cylindrical spectacles, but in his case rarely are, because of the convenience of not needing to wear distance glasses in daily life anymore. The perceptual changes concern color vision, stereopsis and visual acuity. The post-cataract changes were partly expected, for example less yellow and more blue images, but partly wholly unexpected, and accompanied by feelings of excitement and pleasure; even delight. These unexpected changes were a sudden, strongly increased depth vision and the sensation of seeing suddenly sharper than ever before, mainly at intermediate viewing distances. The visual acuity changes occur after, exceptionally, his distance glasses are put on. All these sensations lasted or last only for a short time. Those concerning stereopsis were dubbed 'super depth', and were confined to the first two months after the second cataract operation. Those concerning acuity were termed 'super-sharpness impression'; SSI. These can be elicited more or less at will, by putting on the spectacles described; but will then disappear again, although the spectacles are kept on. Ten other ex-cataract patients have been interviewed on their post-operation experiences. The 'super-depth' and SSI experiences may be linked to assumed neurophysiological mechanisms such as the concept of Bayesian reweighting of perceptual criteria..\u3c/p\u3

Multimedia workstations for the office

Human factors research was carried out on the application of speech in three areas of man-computer communication: instruction, voice commands for system control and annotation of documents. As to instruction, learning was found to proceed equally fast with speech and text; a number of s ubjects preferred speech to text. Secondly, in speech-to-text conversion, subjects preferred voice to manual tommancls for layout and typographic control, although text input was slower with voice than with manual commands. Thirdly, voice annotations are more readily made than script annotations, but processing times may be longer for voice than for script annotations. In conclusion, speech is a valuable medium for human-computer interaction, provided the applications are carefully chosen and a proper user interface is made

On learning stereotyped responses

No abstract

Analysis of keying errors

The performance of keyboard operators can be expressed in terms of keying time and errors; this paper deals with errors. If the causes of errors wore known, it might be possible to reduce the percentage of wrong keystrokes. Therefore, an attempt was made to identify these causes by classifying 293 errors, collected in a field study, into seven categories. About 25% of the errors wore duo to the operator misinterpreting input data; better data presentation may decrease this percentage. At least 40% of the keying errors could bo traced to underlying errors in finger movement control, and would not seem amenable to direct error decreasing measures. Automatic punching of repetitive information brings about numerous repetitive errors as well; improved instructions on the use of programmed punching facilities may reduce these errors

Space, colour and typography on visual display terminals

Some guidelines are given to meet the observed need for rules about layout, the use of colour and typography on display screens so as to create texts with optimal legibility. Examples of videotex pages are used to illustrate right and wrong layouts, applications of colour and of letter type. The guidelines can be generalized to other types of display such as those used in personal computers and, to a more limited extent, to the use of graphics instead of text. Finally, figures are given on the general public's subjective appreciation of some alternative display layouts

Human factors engineering of interfaces for speech and text in the office

Current data-processing equipment almost exclusively uses one input medium: the keyboard, and one output medium: the visual display unit. An alternative to typing would be welcome in view of the effort needed to become proficient in typing; speech may provide this alternative if a proper spe