long-term memory is well established in newborns, which was novel idea in 1965. Keen and her colleagues also performed research on how premature newborns (gestational age 28 weeks to 32 weeks) reacted to painful stimulation (physiological and behavioral responses to heel-sticks). By observing facial expressions, cardiac reactions and movement durations, it was determined that the preterm newborns learned to anticipate the painful stimulus. Some of her research on psychoacoustics focused on the auditory precedence effect. The auditory precedence effect refers to the judgment of a direction of a sound source, which depends on spatial information (i.e., where the sound is coming from). When two sounds are closely space in time, people often hear them as fused, and perceive them as coming from the direction of the first sound. Keen's research indicated that the auditory precedence effect was not present in two-month-old babies but was evident in older babies (four- to six-month-olds). One line of Keen's research focused on how infants and young children solve problems. In a series of clever studies, Keen and colleagues explored problem solving by asking infants to grip various sound-emitting objects in the dark. By contrasting how infants solved problems in different lighting conditions, Keen was able to determine the extent to which infants were relying on vision to solve problems. These studies also demonstrated the infant's mental preparation to grasp objects varying in size even when the objects were no longer visible in the dark. Keen and her colleagues also looked at how infants adjusted their grips in preparation to use different tools. They found that by 14 months of age, infants were using different grips for different tools and action plans, suggesting that they were capable of planning in relation to a goal. Another one of her studies explored how instructions to visualize an event helped three-year-old children solve spatial problems. This study indicated that three-year-olds could use their imagination to help them to solve difficult problems. Representative Publications Clifton, R. K. (1974). Heart rate conditioning in the newborn infant. Journal of Experimental Child Psychology, 18(1), 9-21. Clifton, R. K. (1987). Breakdown of echo suppression in the precedence effect. The Journal of the Acoustical Society of America, 82(5), 1834–1835. Keen, R. (2003). Representation of objects and events: Why do infants look so smart and toddlers look so dumb? Current Directions in Psychological Science, 12(3), 79–83. Keen, R. (2011). The development of problem solving in