The Gibsonian ecological theory of development is a theory of development that was created by American psychologist Eleanor J. Gibson during the 1960s and 1970s. Gibson emphasized the importance of environment and context in learning and, together with husband and fellow psychologist James J. Gibson, argued that perception was crucial as it allowed humans to adapt to their environments. Gibson stated that "children learn to detect information that specifies objects, events, and layouts in the world that they can use for their daily activities". Thus, humans learn out of necessity. Children are information "hunter–gatherers", gathering information in order to survive and navigate in the world. Key concepts Gibson asserted that development was driven by a complex interaction between environmental affordances and the motivated humans who perceive them. For example, to an infant, different surfaces "afford" opportunities for walking, crawling, grasping, etc. As children gain motor skills, they discover new opportunities for movement and thus new affordances. The more chances they are given to perceive and interact with their environment, the more affordances they discover, and the more accurate their perceptions become. Gibson identified four important aspects of human behavior that develop: Agency—Self-control, intentionality in behavior Agency is learning to control both one's own activity and external events Babies learn at an early age that their actions have an effect on the environment For example: Babies were observed kicking their legs at a mobile hanging above them. They had discovered their kicking made the mobile move. Prospectivity—Intentional, anticipatory, planful, future-oriented behaviors For example: A baby will reach out to try and catch an object moving toward them because the baby can anticipate that the object will continue to move close enough to catch. In other words, the baby perceives that reaching out his/her hand will afford him/her to catch the object. Search for Order—Tendency to see order, regularity, and pattern to make sense of the world For example: Before 9 months, infants begin to recognize the strong-weak stress patterns in their native language Flexibility—Perception can adjust to new situations and bodily conditions (such as growth, improved motor skills, or a sprained ankle) Examples: Three-month-old infants lying under a mobile had a string attached to their right leg and then to the mobile so that when they moved their leg the mobile would move. When the string was switched to the left legs, the infants would easily shift to moving that leg