The Perceptual Development “Window” In the First Year of Life

By Cheuk-Yin Lee and Shiyun Wang

Early-life development is extremely critical to future development as it sets up a foundation that allows us to continue building on through our development. We can picture our development as a pyramid. We are born to absorb any languages and recognize any faces, as we grow older, our mind starts to narrow down to what is most essential in our environment. In other words, we specialize and become an expert in our surroundings. 

Adults are better at differentiating faces that are frequently encountered, compared to faces that are infrequently encountered. Although the predominant exposure to faces from our surroundings allows us to become specialists in recognizing different faces, we also lose the ability to differentiate faces that are infrequently exposed in our environment. Kelly et al. (2007) assessed whether infants at different ages would be able to discriminate faces from different ethnicities. The study used a visual paired comparison task (VPC) which allows experimenters to examine infants’ novelty preference by measuring their attention span on viewing a new image compared to an image they have previously seen. In that sense, if an infant could discriminate between both faces shown on the screen, they would show no preference between the two images as both faces demonstrated novelty. In contrast, if the infants only show preference to one of the two faces, it indicates that the children are able to discriminate the face they pay more attention to as the novelty attracts infants’ attention. 

The result of Kelly et al. (2007) indicated that the 3-months-old infants did not demonstrate the other-race effect (ORE), which is the tendency to favor one’s racial group over the other-race group (Meissner & Brigham, 2001). However, the result reported that the ORE emerged at age 6 months and fully presented at 9-months. In other words, 9-months-old infants only showed preference to faces within their ethnic group. 

The study (Kelly et al., 2007) found that infants’ biased attention to faces of their own ethnic group were not due to racial preferences. Instead, the novelty preference was due to the predominant exposure to faces within our environment which allows us to become experts in discriminating faces that are within our environment, compared to other groups that are infrequently encountered. The observation that ORE is not fully acquired until 9-months old indicates that infants were born to learn about different faces, and the constant input from the environment helps us specialize in faces that are considered essential to us. 

The acquired distinctiveness and similarity were also found in languages. Previous studies (Werker & Tees 1983, 1984) have demonstrated that infants were better at distinguishing a foreign language compared to adults. Werker and Tees (1983) compared English infants, English adults, and Hindi adults on their ability to discriminate Hindi speech that was not commonly used in English. For example, the Hindi unvoiced unaspirated retroflex/dental contrast /ṭa/ and /ta/ were commonly used in Hindi speech, but not very in English speech. The study used the head-turn preference procedure (HPP) to measure infants’ ability to distinguish phonemes in English speech and phonemes in Hindi speech. If an infant could identify the differences between speeches, they would turn their head toward the attention attracter (e.g., A bear toy, flashing light). If the infants could not identify the differences, they would be habituated and look away. 

The result (Werker and Tees., 1983) indicated that 6-8 months old English infants’ ability to distinguish Hindi speed matches the Hindi adults. However, English adults were not able to identify the differences between the two different Hindi speeches. To examine the time window for the decline of speech discriminative ability, Werker and Tees (1984) conducted a longitudinal study, and they found that 6-8 months infants were able to discriminate both English and non-English speech. The ability started to decline at 8-10 months old, and by 10-12 months infants lost the ability to discriminate phonemes in Hindi speech. 

The findings from the previous studies (Werker & Tees., 1983, 1984) pointed out that infants can discriminate many different phonemes across multiple languages without relevant experience, but the ability declines by the end of the first year of life. It illustrated that infants were able to identify a variety of languages, and this ability declined as a function of specific language experience. Since the brain has lost the ability to distinguish the phonemes in a newly learned language, it explained why an individual would carry an accent when using a language that is learned later in life, compared to individuals who learned a new language early in life. 

 The above studies illustrated that early life, especially the first year of life is critical and essential for our development. It helps us build a foundation for future development. More importantly, it demonstrated how genetics and the environment impacted us correspondingly throughout our development — we were precoded to learn everything from our environment, and the environment narrowed us down to the elements that were considered the most important in our surroundings. 


Kelly, D. J., Quinn, P. C., Slater, A. M., Lee, K., Ge, L., & Pascalis, O. (2007). The other-race effect develops during infancy: Evidence of perceptual narrowing. Psychological Science, 18(12), 1084-1089.

Meissner, C. A., & Brigham, J. C. (2001). Thirty years of investigating the own-race bias in memory for faces: A meta-analytic review. Psychology, Public Policy, and Law, 7(1), 3.

Werker, J. F., & Tees, R. C. (1983). Developmental changes across childhood in the perception of non-native speech sounds. Canadian Journal of Psychology/Revue canadienne de psychologie, 37(2), 278.

Werker, J. F., & Tees, R. C. (1984). Cross-language speech perception: Evidence for perceptual reorganization during the first year of life. Infant behavior and development, 7(1), 49-63.