Perceptual Narrowing

Perceptual narrowing—characterized as broad perception from birth which narrows as a function of experience—has previously been tested with primate faces. In the first six months of life, infants can discriminate individual human and monkey faces. Though the ability to discriminate monkey faces declines by about nine months, infants retain human face discrimination, presumably due to their experience with human faces. The current study demonstrates that 4- to 6-month-old infants are able to discriminate non-primate faces as well. In a visual paired comparison test, 4- to 6-month-old infants (N = 26) looked significantly longer at novel sheep (Ovis aries) faces, compared to a familiar sheep face (p = .017), whereas 9- to 11-month-olds (N = 26) showed no visual preference, and adults (N = 27) showed a familiarity preference (p < .001). Infants’ face recognition systems are broadly tuned at birth—not just for primate faces, but for non-primate faces as well—allowing infants to become specialists in recognizing the types of faces encountered in their first year of life.

Human infants become native-language listeners through a process of perceptual narrowing. Monolingual infants are initially sensitive to a wide range of language-relevant contrasts. However, as they mature and gain native-language experience, their sensitivity to non-native contrasts declines. Here, we consider the case of infants growing up bilingual as a window into how increased variation affects early perceptual development. These infants encounter different meaningful contrasts in each of their languages, and must also attend to contrasts that occur between their languages. Bilingual infants share many classic developmental patterns with monolinguals. However, they also show unique developmental patterns in the perception of native distinctions such as U-shaped trajectories and dose-response relationships, and show some enhanced sensitivity to non-native distinctions. Analogous developmental patterns can be observed in individuals exposed to two non-linguistic systems in domains such as music and face perception. Some preliminary evidence suggests that bilingual individuals might retain more sensitivity to non-native contrasts, reaching a less narrow end state than monolinguals. Nevertheless, bilingual infants do become perceptually-specialized native listeners to both of their languages, despite increased variation and differing patterns of perceptual development in comparison to monolinguals.

Computer-modeled characters resembling real people sometimes elicit cold, eerie feelings. This effect, called the uncanny valley, has been attributed to uncertainty about whether the character is human or living or real. Uncertainty, however, neither explains why anthropomorphic characters lie in the uncanny valley nor their characteristic eeriness. We propose that realism inconsistency causes anthropomorphic characters to appear unfamiliar, despite their physical similarity to real people, owing to perceptual narrowing. We further propose that their unfamiliar, fake appearance elicit cold, eerie feelings, motivating threat avoidance. In our experiment, 365 participants categorized and rated objects, animals, and humans whose realism was manipulated along consistency-reduced and control transitions. These data were used to quantify a Bayesian model of categorical perception. In hypothesis testing, we found reducing realism consistency did not make objects appear less familiar, but only animals and humans, thereby eliciting cold, eerie feelings. Next, structural equation models elucidated the relation among realism inconsistency (measured objectively in a 2D Morlet wavelet domain inspired by the primary visual cortex), realism, familiarity, eeriness, and warmth. The fact that reducing realism consistency only elicited cold, eerie feelings toward anthropomorphic characters, and only when it lessened familiarity, indicates the role of perceptual narrowing in the uncanny valley.

Adults detect conspecific faces more efficiently than heterospecific faces; however, the development of this own-species bias (OSB) remains unexplored.  We tested whether 6- and 11-month-olds exhibit OSB in their attention to human and animal faces in complex visual displays with high perceptual load (25 images competing for attention).  Infants (n = 48) and adults (n = 43) passively viewed arrays containing a face among 24 non-face distractors while we measured their gaze with remote eye tracking.  While OSB are typically not observed until about 9 months, we found that, already by 6 months, human faces were more likely to be detected, were detected more quickly (attention capture), and received longer looks (attention holding) than animal faces. These data suggest that 6-month-olds already exhibit OSB in face detection efficiency, consistent with perceptual attunement. This specialization may reflect the biological importance of detecting conspecific faces, a foundational ability for early social interactions.

This experimental study examined bilingual (English and another noun-dominant language) and monolingual (English) preverbal (10.5-month-old) and postverbal (12.5-month-old) infants' word-action mapping. Sixteen infants in each group were habituated to dynamic video-displays of novel word-action pairings during infant-controlled habituation. They received two words, /wem/ and /baef/, spoken synchronously with an adult shaking or looming an object, and were tested with switched versus same word-action pairings. Results revealed that for the preverbal bilingual infants, word-action mapping is intensified relative to postverbal bilingual infants. For the postverbal bilingual infants, word-action mapping is attenuated and inversely correlated with noun learning. No such differences were observed in the monolingual infants. These findings illustrate a perceptual protraction prior to word production and accelerated perceptual narrowing to nouns after word production in bilingual infants learning two noun-dominant languages.

Learned attention models of perceptual discrimination predict that with age, sensitivity will increase for dimensions of stimuli useful for discrimination.  We tested this prediction by examining the face dimensions 4- to 6-month-olds (n = 77), 9- to 12-month-olds (n = 66), and adults (n = 73) use for discriminating human, monkey, and sheep faces systematically varying in outer features (contour), inner features (eyes, mouth), or configuration (feature spacing).  We controlled interindividual variability across species by varying faces within natural ranges and measured stimulus variability using computational image similarity.  We found the most improvement with age in human face discrimination, and older participants discriminated more species and used more facial properties for discrimination, consistent with learned attention models.  Older infants and adults discriminated human, monkey, and sheep faces; however, they used different facial properties for primates and sheep.  Learned attention models may provide insight into the mechanisms underlying perceptual narrowing.

Recent data demonstrate a perceptual processing advantage for adult faces in both adults and young children, suggesting that face representation is shaped by visual experience accumulated with different face-age groups. As for species and race, this age bias may emerge during the first year of life as part of the general process of perceptual narrowing, given the extensive amount of social and perceptual experience accumulated with caregivers and/or other adult individuals. Using infant-controlled habituation and visual-paired comparison at test, two experiments were carried out to examine 3- and 9-month-olds&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; ability to discriminate within adult and infant faces. Results showed that, when they are provided with adequate time to visually compare the stimuli during test trials (Experiment 2), 3-month-olds exhibit above-chance discrimination of adult and infant faces. Instead, 9-month-olds discriminate adult faces but not infant faces (Experiments 1 and 2). Results provide the first evidence of age-related face processing biases in infancy, and show that by 9 months face representations tune to adult human faces.

Initially, infants are capable of discriminating phonetic contrasts across the world&#39;s languages. Starting between seven and ten months of age, they gradually lose this ability through a process of perceptual narrowing. Although traditionally investigated with isolated speech sounds, such narrowing occurs in a variety of perceptual domains (e.g., faces, visual speech). Thus far, tracking the developmental trajectory of this tuning process has been focused primarily on auditory speech alone, and generally using isolated sounds. But infants learn from speech produced by people talking to them, meaning they learn from a complex audiovisual signal. Here, we use near-infrared spectroscopy to measure blood concentration changes in the bilateral temporal cortices of infants in three different age groups: 3-to-6 months, 7-to-10 months, and 11-to-14-months. Critically, all three groups of infants were tested with continuous audiovisual speech in both their native and another, unfamiliar ...

Exposure to faces is known to shape and change the face processing system; however, no study has yet documented infants&#39; natural daily first-hand exposure to faces. One- and three-month-old infants&#39; visual experience was recorded through head-mounted cameras. The video recordings were coded for faces to determine: (1) How often are infants exposed to faces? (2) To what type of faces are they exposed? and (3) Do frequently encountered face types reflect…

Learned attention models of perceptual discrimination predict that with age, sensitivity will increase for dimensions of stimuli useful for discrimination. We tested this prediction by examining the face dimensions 4- to 6-month-olds (n = 77), 9- to 12-month-olds (n = 66), and adults (n = 73) use for discriminating human, monkey, and sheep faces systematically varying in outer features (contour), inner features (eyes, mouth), or configuration (feature spacing). We controlled interindividual variability across species by varying faces within natural ranges and measured stimulus variability using computational image similarity. We found the most improvement with age in human face discrimination, and older participants discriminated more species and used more facial properties for discrimination, consistent with learned attention models. Older infants and adults discriminated human, monkey, and sheep faces; however, they used different facial properties for primates and sheep. Learned attention models may provide insight into the mechanisms underlying perceptual narrowing.

Perceptual narrowing has been observed in human infants for monkey faces: 6-month-olds can discriminate between them, whereas older infants from 9 months of age display difficulty discriminating between them. The difficulty infants from 9 months have processing monkey faces has not been clearly identified. It could be due to the structural characteristics of monkey faces, particularly the key facial features that differ from human faces. The current study aimed to investigate whether the information conveyed by the eyes is of importance. We examined whether the presence of Caucasian human eyes in monkey faces allows recognition to be maintained in 6-month-olds and facilitates recognition in 9- and 12-month-olds. Our results revealed that the presence of human eyes in monkey faces maintains recognition for those faces at 6 months of age and partially facilitates recognition of those faces at 9 months of age, but not at 12 months of age. The findings are interpreted in the context of ...

The present study tested infants from English-speaking homes to examine effects of development on cross-language speech perception. Werker (1981, 1984) showed that 6-8-month-old infants are able to discriminate non-native speech sounds that adults cannot discriminate, but by 10-12 months the infants were no longer able to make the discrimination. According to Kuhl (2004, 2008), this decline in discrimination is due to infants? increase in native-language exposure, which leads to ?neural commitment? to the native language at this age. Many studies have shown a decline in discriminatory abilities of infants for non-native contrasts between 6 - 12 months of age but no study to date has tested a contrast in affricates in a cross-language perception test. Also, very little attempt has been made to show whether the experimental order of presentation of stimuli affects infants? performance. An aspirated - unaspirated contrast of Urdu /t?/ - /t?h/ was selected based on a pilot study with 20 English-speaking adults who were tested on a number of Urdu contrasts not found in English to identify the most difficult. Twenty-four 7- and 11-month olds were tested in a habituation procedure. Half of the infants were habituated to the voiceless aspirated affricate and tested on the contrasting voiceless unaspirated affricate while the remaining infants experienced the reverse pattern. Discrimination was assessed by comparing mean looking time during the last two habituation trials to mean looking time during the first two trials of the test phase. In agreement with the literature, the results indicated that 6-8-month-olds could discriminate the affricate pair but 11-month-olds could not. Infants presented with the non-prototypical consonant (the aspirated affricate, which does not occur in English) in the habituation phase showed better discrimination in the test phase than the infants presented with the prototypical consonant in the habituation phase.