A-Not-B Task

Cognitive development theorists investigate and report how children think, explore, and interpret situations. This entails the thought processes its changes as a child develops through developmental stages. Hence, intelligence, information processing, memory, language development, and reasoning are studied in cognitive development. Earlier on, children were considered to have limited thought capabilities. However, some scientists, including Jean Piaget, later found exciting realities in cognitive development. First, an infant’s cognitive capabilities developed in phases, which would become Piaget’s four stages of cognitive development. Secondly, human intelligence improved through these stages. At some point, infants gained intelligence by interacting with the world around them through sensations. This is measured by assessing object permanence, using tests such as the A-Not-B task.

Object permanence describes a child’s ability to perceive that an object they have seen exists even if they cannot see it or hear from it anymore. The age of a child in this context is taken to be between eight and twelve months. Thus, object permanence is a characteristic of the human development state – sensorimotor stage. Before this stage, a child cannot know if an object exists. For instance, if an object, say a toy, is placed under the banket, a child would think it has disappeared. However, children’s cognitive ability is advanced at the sensorimotor stage, and thus, if an object is covered with a blanket, the child will know that it exists (Yates & Bremner, 1988). This is the first version of an experiment to test object permanence, which psychologist Jean Piaget found when founding cognitive development theory. It would become one of the most excellent methods for measuring cognitive developmental milestones in childhood. Children who have acquired object permanence are more cognitively developed than those who have not (Cherry, 2019). It is imperative to note that this experiment particularly tests a child’s cognitive development in reference to their visual attentiveness (Horobin & Acredolo, 1986). That is why in Piaget’s experiment, a child would be shown a toy; then the toy got hidden to see if the child would notice the disappearance and, if they noted, where they would search for the toy. Results for this experiment are somewhat fascinating, as described in the A-Not-B Task literature.

            In Piaget’s experiment, some infants make an A-Not-B error. This is how the error was found: infants aged 8-12 months were shown a toy. The toy was then covered (hidden) on one side called A. The infant was allowed to search the toy, and they autonomously searched the toy to the side A. The experimenter then took the toy and hid (covered) the toy on the opposite side of A, called B. The infant was then allowed to search the toy. Again, the infant immediately and autonomously searched the toy on side B. However, Piaget (1954) noted that if a delay to search was imposed on the infant, nearly half of the infants autonomously searched the toy to the side A, and not B, which is erroneous. Further, when the toy was not covered in the second step of the experiment, only a few infants made the error.

Piaget’s results were replicated in later studies, such as Horobin & Acredolo (1986), who tested the factors that influenced the A-Not-B Task error. The study concluded that spatial separation of hiding sites, visual attentiveness, and length of time before an infant is allowed to search an object are significant determinants for the A-Not-B Task error. These changes have been discussed in the context of developmental milestones, where self-produced mobility and extensiveness of spatial experience are rated with respect to visual attentiveness and search performance. Thus, several cognitive development theories are based on the A-Not-B Task error, such as the Piaget development theory and Siegler overlapping waves theory.

According to Jean Piaget’s theory of cognitive development, children undergo four stages of mental development, from which object permanence and the A-Not-B error are illustrated. The main theme in this theory is how children acquire knowledge and the changes that happen to intelligence as a child grows (Hugar et al., 2017). Intelligence and knowledge in children are not merely smaller versions of adults’, but they develop as children increase in age. According to Piaget, the changes are mapped into four stages, namely the sensorimotor stage: birth to 2 years, preoperational stage: ages 2 to 7, concrete operational stage: ages 7 to 11, and formal operational stage: ages 12 and up (Piaget, 1954). Within these states, Piaget hypothesized that intelligence can be quantified and that children are not less intelligent, but rather, they think differently. In the sensorimotor stage, infants learn and know the environment through sensation – sucking, grasping, looking, and listening. It is at this stage that they develop object permanence (Yates & Bremner, 1988). For instance, through visualization, infants become aware of objects and their proximities. Ahmed & Ruffman (1998) found that the more a child looked at an object in Piaget’s experiment, the less they were likely to commit the A-Not-B error. This has been summed as familiarization by Yates & Bremner (1988), who contend that the more an infant is familiarized with an object (the world), they learn and understand it and commit less A-Not-B errors. According to Piaget (1954), the sensorimotor stage ends with the development of object permanence – when a child knows that an object continues to exist even if they can not identify it by any of their sensations. Then they develop into the preoperational stage, where they can present things symbolically and use some words. Children learn and use many skills but continue to perceive the world concretely.

Siegler’s overlapping waves theory also provides a perspective on the development of object permanence and A-Not-B error. The theory is based on the assumption that (1) children think about a phenomenon in a variety of ways at any given time, (2) those ways of thinking are in constant self-justification, which results in a prolonged competition of thoughts, and (3) the frequency of the thoughts changes through human development, and so does the completion in assumption two (Chen & Siegler, 2000). In a former study, Yates & Bremner (1988) had attempted to connect Siegler’s overlapping waves theory with the development of object permanence and A-Not-B task error. They cited that different memory interpretations cause the A-Not-B task error for the object. In the same year, Ahmed & Ruffman (1998) cited that object A was held in the long-term memory, while object B was held in short-term memory. Thus, in the perspective of Siegler’s (1996) second assumption, the short term and the long term memories (memory of object at A and memory of the object at B) compete to reveal a sensation during the object search. Since the child had significantly interacted with the object at A than at B, they are more likely to search at A and not at B. However, this competition for varied ways of thinking reduces as the child develops sophisticated cognitive abilities in the other three stages of Piaget’s cognitive development theory.


To sum up, object permeance and the A-Not-B task error are common in the IV stage of development. Object permeance is the child’s ability to know that an object exists even though they can no longer see, feel, or touch it. This idea has been used to measure developmental milestones, using an experiment initially used by Piaget (1954). In his experiment, Piaget notices an error, where infants searched for the object on the wrong side. The error is explained in his theory that infants learn the world around them by sensations to increase intelligence by familiarization in the sensorimotor stage. Siegler adds that an infant has varied memories at that stage through the overlapping waves theory, which often compete with justifications.


Piaget, J. (1954). The construction of reality in the child (pp. 44-66). New York: Routledge

Ahmed, A., & Ruffman, T. (1998). Why Do Infants Make A Not B Errors in a Search Task, Yet Show Memory for the Location of Hidden Objects in a Nonsearch Task?. Developmental Psychology, 34(3), 441-453. https://doi.org/10.1037/0012-1649.34.3.441

Chen, Z., & Siegler, R. (2000). II. Overlapping Waves Theory. Monographs Of The Society For Research In Child Development, 65(2), 7-11. https://doi.org/10.1111/1540-5834.00075

Cherry, K. (2019). How Infants Know That Unseen Objects Continue to Exist. Verywell Mind. Retrieved 8 December 2020, from https://www.verywellmind.com/what-is-object-permanence-2795405#citation-1.

Horobin, K., & Acredolo, L. (1986). The role of attentiveness, mobility history, and separation of hiding sites on stage IV search behavior. Journal Of Experimental Child Psychology, 41(1), 114-127. https://doi.org/10.1016/0022-0965(86)90054-8

Hugar, S., Kukreja, P., Assudani, H., & Gokhale, N. (2017). Evaluation of the Relevance of Piaget’s Cognitive Principles among Parented and Orphan Children in Belagavi City, Karnataka, India: A Comparative Study. International Journal Of Clinical Pediatric Dentistry, 10(4), 346-350. https://doi.org/10.5005/jp-journals-10005-1463

Yates, D., & Bremner, J. (1988). Conditions for Piagetian Stage IV search errors in a task using transparent occluders. Infant Behavior And Development, 11(4), 411-417. https://doi.org/10.1016/0163-6383(88)90002-1