Affordance: the match between the body and the environment that makes a particular action possible. Gibson (1979)
Actions can succeed only if they are scaled to the properties of the body and the environment. For example, reaching through an opening is possible only if the hand is smaller than the opening.
Perceiving affordances can be characterized by sensitivity, accuracy, and consistency. (Ishak et L 2014)
Sensitivity refers to the ability to detect the critical body–environment relations
Accuracy refers to the match between the actual affordance and participants' decisions.
'Accuracy is necessary to ensure that selected actions are appropriate given the properties of the body and environment. Errors in action selection, such as trying to fit through openings that are too small, can have dire consequences for safety. Accuracy can be influenced by sensitivity and by differences in response criteria such as how heavily one weights the penalty for error." Ishak et al 2014
Affordance perception must be consistent over successive encounters. For example, attempting and refusing to fit through the same opening on successive presentations reflects a lack of consistency.
Development of affordance perception
Infants and children must learn to perceive affordances accurately. When they first acquire new skills, infants' decisions about possible and impossible actions are rife with errors, but over weeks of experience practicing their new skills, decisions become increasingly accurate.
For example, novice walkers attempted to descend impossibly steep slopes and cliffs (requiring rescue from an experimenter to prevent injury). Over weeks of walking, decisions gradually geared in to infants' actual abilities. Experienced walkers made accurate decisions by refusing to descend or by switching to an alternative sliding or backing position (Adolph, 1997; Kretch & Adolph, 2013a, 2013b).
Infants will often use touching behaviors to explore a situation when thet are uncertain, such as patting a surface to find out about firm, touching the circumference of an opening before attempting to insert the hand (Ishak et al 2014).
References and suggested reading
Comalli DM, Persand D, Adolph KE. Motor decisions are not black and white: selecting actions in the "gray zone". Exp Brain Res. 2017 Jun;235(6):1793-1807. PDF
Franchak, J. M., & Adolph, K. E. (2012). What infants know and what they do: Perceiving possibilities for walking through openings. Developmental Psychology, 48(5), 1254–1261. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3584587/
Franchak, J., & Adolph, K. (2014). Affordances as Probabilistic Functions: Implications for Development, Perception, and Decisions for Action. Ecological Psychology : A Publication of the International Society for Ecological Psychology, 26( 1-2), 109–124. http://doi.org/10.1080/10407413.2014.874923
Ishak, S., Franchak, J. M., & Adolph, K. E. (2014). Perception–action development from infants to adults: Perceiving affordances for reaching through openings. Journal of Experimental Child Psychology, 117, 92–105. http://doi.org/10.1016/j.jecp.2013.09.003
Oudgenoeg-Paz O, Boom J, Volman MC, Leseman PP. (2016)Development of exploration of spatial-relational object properties in the second and third years of life. J Exp Child Psychol. 2016 Jun;146:137-55. doi: 10.1016/j.jecp.2016.02.005. Epub 2016 Mar 4. PubMed PMID: 26950506.