NASASpace Station missions will include crewmembers who are highly experienced in the use of the Space Station computer system, as well as others who are novices. Previous research into novice-expert differences has strongly implied that user interface changes that aid novices tend to impair experts and vice versa. This experiment investigated the impact reformatting alphanumeric information on current Space Shuttle computer displays had on the speed and accuracy of experts and nonexperts in two different search tasks.Large improvements in speed and accuracy were found for nonexperts on the reformatted displays. Experts had fewer errors but no response time difference on the reformatted displays. Differences in expert and nonexpert search strategies and implications for the design of computer displays are discussed.

American manned spacecraft have used a l a r g e number of d i s c r e t e dedicated switches In t h e decade and buttons t o allow astronauts t o monitor and control system functions.or so since t h e Space S h u t t l e was designed, t h e r e have been many improvements i n t h e area of control m u l t i f u n c t i o n a l i t y . One of these advances i s t h e development of programmable display pushbuttons (PDPs), which a r e illuminated pushbuttons w i t h displays c o n s i s t i n g of a matrix of LEDs t h a t can show preprogrammed information i n the form of alphanumerics or symbols. Our work i s designed t o study t h e parameters a f f e c t i n g t h e usefulness of PDPs i n manned space operations. complex Space S h u t t l e tasks by comparing c u r r e n t procedures and procedures involving the use of PDPs. user-PDP i n t e r f a c e for one typical Space S h u t t l e t a s k . We a r e simulating t h e performance of This paper discusses issues t h a t arose i n t h e course of designing the I NTRODUCTI ON Throughout t h e h i s t o r y of t h e American space program, manned spacecraft have used a l a r g e number of d i s c r e t e dedicated switches and buttons t o allow astronauts t o monitor and cont r o l system functions. The Space S h u t t l e cockp i t , f o r example, contains approximately 1500 switching devices, 300 annunciators, and 40 meter/electromechanical displays f o r status information and subsystem control operations. Many of these devices a r e required only d u r i n g s p e c i f i c phases of t h e mission. was designed, t h e r e have been numerous advances i n d i s p l a y and control technology. Many of these advances have been i n t h e area of control m u l t i f u n c t i o n a l i t y ; t h a t i s , providing t h e capab i l i t y f o r one piece of hardware t o serve mu]-t i p l e functions i n d i f f e r e n t modes of operation. Knowlton (1977) describes a method f o r o p t i c a l l y superimposing computer displays on i n p u t devices. This procedure can be used t o make computergenerated l a b e l s appear t o be temporarily i nscribed on a s e t of pushbuttons a t a console. Changes i n t h e software allow switching from one mode t o another, a s t h e v i s i b i l i t y , posit i o n , l a b e l , s i g n i f i c a n c e , and function of each button a r e under software c o n t r o l . In t h e decade or so since t h e Space S h u t t l e Nakatani and Rohrlich (1977) discuss t h e concept o f s o f t machines, machines t h a t use a combination of real-time computer graphics and a touch-sensitive position sensor coup1 ed with a video display terminal (touch s c r e e n ) . The graphics software makes t h e s o f t machine look l i k e a conventional hard machine through t h e generation of images of c o n t r o l s shown on t h e video display terminal ( e . g . , keys, pushbutton switches, and s l i d e potentiometers). screen enables t h e user t o touch and operate t h e s o f t c o n t r o l s i n the display a s i f they were hard c o n t...