Through a series of tests on infants, Woodward has established that children begin to develop reasoning skills as young as seven months of age and are able to comprehend words equally well at 13 months as they do at 1 months, when they begin to speak with an expanded vocabulary.
Her work expands what is known about early learning ability and offers the prospect of understanding the conditions that lead to serious developmental disorders such as autism.
Woodward's research will be supported during the next four years by the John Merck Fund of Boston, which this spring named Woodward one of three scholars nationally to receive $240,000 grants over four years. The John Merck Scholars Program is intended "to stimulate gifted, young neurobiologists and cognitive scientists to direct their attention to the problems of the mentally handicapped and emotionally disturbed child," the foundation said.
"I've always been interested in how skills develop," said Woodward, who joined the faculty in the Fall."I want to find out, for instance, how the ability to understand language develops."
Swiss psychologist Jean Piaget and older researchers have contended that babies are largely undeveloped mentally at he age of six months and learn by exposure to adult stimulation. Woodward is discovering, however, that babies understand a great deal about their world by that
Woodward began her research in cognitive development at Swarthmore College, where she received a B.A. in psychology in 1987. As a graduate student at Stanford, her work focused on reasoning in infants. She completed her Ph.D. in psychology at Stanford in 1992, and spent a year studying as a postdoctoral fellow at Cornell University before coming to Chicago.
In her work at Cornell, Woodward tested the idea that children make distinctions between the way they expect inanimate objects to react to each other and the way they anticipate humans will react to each other.
She conducted tests on seven-month-old babies to assess their reasoning skills using a test that measured their attention span to different events. The method, called visual habituation, has been used to determine infant understanding of the actions of inanimate objects.
Researchers have found, for instance, that by measuring how long a baby watches a particular event, they can determine if the baby is surprised by what happens. The longer a baby watches, the more likely it is the baby is trying to understand a situation he or she does not expect to happen.
Tests on objects show, for instance, that babies tend to expect that objects are moved by coming into contact with each other. During the first test, the babies watch a videotape in which an object comes from the left and moves behind a screen that blocks the babies' view of the action. Another object on the tape moves off the screen after the first object enters.
In the second test, the screen is remove to show the two objects colliding and not colliding before the second object moves. Because babies watch the activity longer when the objects do not collide, researchers concluded they are surprised by the action because it violates a principle they have learned: in order for objects to cause other objects to move, they must touch each other.
But what about humans? If babies are similarly surprised when humans move without touching, their response would probably indicate that they expect humans and objects to react to each other in the same way.
Woodward and her colleagues conducted the object tests with youngsters and found that they reacted as expected. When they substituted human beings for the objects in the tests, the youngsters made no distinction in the time they spent watching the two encounters. They spent equal time watching humans bump into each other before being moved as they did watching humans move in response to each other without touching.
"The findings support the conclusion that by seven months, infants differentiate between people and objects in their reasoning about simple causal sequences," Woodward said, in a paper co-authored with Ann Phillips and Elizabeth Spelke. The paper, "Infants' Expectations about the Motion of Animate versus Inanimate Objects," was presented in 1993 to a meeting of the Cognitive Science Society.
"This suggests that, by this age, infants may have a separate set of principles to guide their reasoning about human action and, with more empirical work, we may be able to determine what these principles are," she reported.
A critical stage of child development comes when infants begin using a greatly expanded vocabulary. This huge increase in word usage typically takes place somewhere between the ages of 18 and 24 months.
"Even to the casual observer, the differences in the linguistic abilities of one year-olds and two-year-olds are striking," Woodward writes in "Rapid Word Learning in 13- and 18-month-olds" to be published later this year in the journal Developmental Psychology. "The average one year-old is just beginning to produce words, whereas the average two-year-old has a large productive vocabulary and has begun to produce multiword utterances," she writes.
Many researchers have contended that the naming explosion is the result of a new understanding on the part of children that words are symbols which refer to entities in the world. A change in comprehension therefore leads youngsters to cross the bridge from dealing laboriously with word acquisition to come to a new level of ability in the way they acquire words.
But Woodward and her co-authors, Ellen Markman and Colleen Fitzsimmons, wondered if there was a change in comprehension that emerged in a baby' s mind at age 18 months. They introduced invented words to children who were before the age of the naming explosion and children who were at this age to see if comprehension changed as youngsters grow older.
The researchers used a large plastic paper clip and a plastic strainer as props and called them tomas in order to prevent the children from being influenced by a word they had previously heard. In some cases, the strainer was called a toma and in other cases, the plastic paper clip was given the invented name.
The researchers repeated the word nine times in different situations for children in each age group. The children were then asked to pick a toma from a tray. The researchers developed a multiple choice test that compensated for age group differences so that 13-month-olds were not unfairly tested, for instance, by being presented with too complicated a task.
Once they developed an age-appropriate test, they found little difference between the rate of word learning and retention between 13-month-olds and 18 month-olds. Children at both ages even remembered the new word after a 24-hour delay.
"These findings argue against theories which posit that the naming explosion is the result of broad changes in word learning competence," Woodward and her colleagues write. Other factors, that relate to the production of words such as improved memory or the ability to articulate successfully, may account for the expanded vocabulary, she suggests.
"The fact that even young infants interact with their caretakers in well orchestrated sequences suggests that infants have the ability to reason and make predictions about the behavior of others," she said In one study, Woodward is interested in determining how soon children begin understanding that actions are goal-directed and guided by perception.
"This research may have applications to developmental disorders such as autism, which are characterized by deficits in language and in reasoning about actions of others," Woodward said.
"The research I have planned will yield an outline of normal infants' conceptions of the actions of social others and their understanding of language as communicative and referential," she said. "A direction for future work will be to assess these concepts in autistic children. This will fill in the picture of what specific abilities autistic children lack and how these deficits affect later development," she said.