Temple Grandin has a newer book titled Visual Thinking. She tells of two groups taught to sharpen flints (IIRC). The first group had instruction only by gesture

Temple Grandin has a newer book titled Visual Thinking. She tells of two groups taught to sharpen flints (IIRC). The first group had instruction only by gestures and example; the second group also had written or spoken instruction. Apparently persons in the first group developed skill faster. Overall she suggests that words can distract from visual observation or attention. IIRC Derrick Jensen refers to an experiment in which apes caught on to cheating behavior faster than humans, presumably because they were not fooled by any spoken claims.