EFFORTS WERE MADE IN THIS STUDY TO (1) RELATE THE AMOUNT OF SILENT SPEECH DURING SILENT READING TO LEVEL OF READING PROFICIENCY, INTELLIGENCE, AGE, AND GRADE PLACEMENT OF SUBJECTS, AND (2) DETERMINE WHETHER THE AMOUNT OF SILENT SPEECH DURING SILENT READING IS AFFECTED BY THE LEVEL OF DIFFICULTY OF PROSE READ AND BY THE READING OF A FOREIGN LANGUAGE. THREE EXPERIMENTS WERE CONDUCTED. FOR THE FIRST EXPERIMENT 36 VACATION BIBLE SCHOOL CHILDREN BETWEEN 6 AND 11 YEARS OF AGE WERE INVOLVED. EXPERIMENT 2 INVOLVED 60 CHILDREN FROM A PUBLIC ELEMENTARY SCHOOL, AND IN THE THIRD EXPERIMENT, 24 FEMALE COLLEGE STUDENTS SERVED AS SUBJECTS. PRIOR TO CARRYING OUT THE EXPERIMENTS, SUBJECTS WERE CLASSIFIED BY READING AND IQ LEVELS, AGE, AND GRADE PLACEMENT. DISA SURFACE ELECTRODES RECORDED CHIN ACTIVITY IN THE FIRST EXPERIMENT. LIP ACTIVITY WAS RECORDED IN THE OTHER TWO EXPERIMENTS. READING MATERIAL WAS PRESENTED AT ONE END OF A VIEWING BOX AND WAS CHANGED BY A SYSTEM OF ROLLERS. MICROPHONES WERE USED TO RECORD ANY AUDIBLE SUBVOCAL SPEECH. MUSCLE ACTION AND BREATHING ACTIVITY WERE RECORDED FOR SOME SUBJECTS. IT WAS CONCLUDED THAT THE ACTIVITY OF SILENT READING EITHER CONSISTS OF, OR RESULTS IN, COVERT LANGUAGE RESPONSES (DEVOTED BY THE TERM "SILENT SPEECH" AS MEASURED BY LIP AND CHIN MOVEMENT, AMPLIFIED SUBVOCALIZATION, AND BREATHING RATE). A TOTAL OF 12 MORE SPECIFIC CONCLUSIONS ARE DISCUSSED. (JC)