THIS STUDY WAS CONDUCTED TO INVESTIGATE THE EFFECTS OF VARIATIONS IN THE SPEED AND DIRECTION OF A FLYING OBJECT ON VISUO-PERCEPTUAL JUDGMENTS MADE, DIFFERENCES IN THE ABILITY OF SKILLED AND UNSKILLED SUBJECTS IN MAKING SUCH JUDGMENTS, AND THE EFFECTS OF AGE OR MATURITY LEVEL ON THE SPEED AND ACCURACY OF SUCH JUDGMENTS. THE SUBJECTS WERE 54 MALE JUNIOR HIGH, HIGH SCHOOL, AND COLLEGE STUDENTS CLASSIFIED AS SKILLED OR UNSKILLED DEPENDING ON EXPERIENCE IN BALL COMPETITIONS, PERFORMANCE ON A VELOCITY TEST, VISUAL ACUITY, AND DEPTH PERCEPTION CAPACITY. THEY WERE ASKED TO JUDGE VISUALLY THE FLIGHT OF A MOVING OBJECT BY CHOOSING AN "OPTIMUM POINT FOR INTERCEPTION" AND QUICKLY MOVING TO THE SELECTED SPOT. FIVE VARIABLES WERE CONSIDERED--(1) SPEED OF PROJECTION, (2) VERTICAL DIRECTION OF PROJECTION, (3) HORIZONTAL DIRECTION OF PROJECTION, (4) SKILL LEVEL, AND (5) AGE OR MATURITY LEVEL. MEASURES INCLUDED A REACTION TIME MEASURE, A MOVEMENT TIME INDEX, AND THREE MEASURES OF SPATIAL ACCURACY OF VISUO-PERCEPTUAL JUDGMENT. RESULTS SHOWED THAT THE SPEED AND ACCURACY WITH WHICH THE FLIGHT OF A MOVING OBJECT WAS JUDGED DEPENDED ON SPEED, THE HORIZONTAL DIRECTION, AND THE VERTICAL DIRECTION IN WHICH THE OBJECT WAS MOVING AT THE TIME OF JUDGMENT. HIGHLY SKILLED SUBJECTS WERE SUPERIOR TO UNSKILLED ONES IN MAKING VISUO-PERCEPTUAL JUDGMENTS. AGE HAD LITTLE OR NO EFFECT. TABLES AND CHARTS ARE INCLUDED. (AUTHOR/NS)