the words: "mama", "papa", "cup" and "up". Over the years she learned to say up to seven words. Viki was extremely intelligent and like many other non-human primates, would lead people to where she wanted to go as well as move the hands of people onto objects she wanted them to manipulate. However, she would rarely point to objects that she wanted; instead she would use signs to indicate what she wanted to do. For example, when she wanted to help with ironing she would move her hand back and forth above the ironing board. This experiment with Viki would inspire other researchers to conduct similar experiments. Question asking Despite their impressive (although still sometimes disputed) achievements, Kanzi and other apes who participated in similar experiments, failed to ask questions themselves. Joseph Jordania suggested that the ability to ask questions is probably the central cognitive element that distinguishes human and animal cognitive abilities. (However, a parrot named Alex was apparently able to ask simple questions. He asked what color he was, and learned "grey" after being told the answer six times.) Enculturated apes, who underwent extensive language training programs, successfully learned to answer quite complex questions and requests (including question words "who", "what", "when", "where", and "why"), although so far they failed to learn how to ask questions themselves. For example, David and Anne Premack wrote: "Though she [Sarah] understood the question, she did not herself ask any questions – unlike the child who asks interminable questions, such as What that? Who making noise? When Daddy come home? Me go Granny's house? Where puppy? Sarah never delayed the departure of her trainer after her lessons by asking where the trainer was going, when she was returning, or anything else". The ability to ask questions is sometimes assessed in relation to comprehension of syntactic structures. Jordania suggested that this approach is not justified, as (1) questioning is primarily a cognitive ability, and (2) questions can be asked without the use of syntactic structures (with the use of specific intonation only). It is widely accepted that the first questions are asked by humans during their early infancy, at the pre-syntactic, one word stage of language development, with the use of question intonation. Criticisms of primate language research Some scientists, including MIT linguist Noam Chomsky and cognitive scientist Steven Pinker, are skeptical about claims made for great ape language research. Among the reasons