The nature and development of early number concepts.
D000367:Age Factors; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D003071:Cognition; D003210:Concept Formation; D003463:Cues; D004193:Discrimination Learning; D005260:Female; D005556:Form Perception; D006801:Humans; D007600:Judgment; D008297:Male; D008433:Mathematics; D011340:Problem Solving; D011582:Psychological Theory; D014705:Verbal Behavior