Perceptual Development

  • Vocabulary

    • Vision: The least developed of the senses at birth, due to lack of control of eye muscles, the structure of the eyes and the brain isn’t fully formed, leading to low acuity

    • Contrast sensitivity: The ability to distinguish contrast and distinguish things in the visual environment, very low in infants

    • Habituation: Decline in response to a stimulus as a response to prolonged exposure

    • Dishabituation: Revived interest in new things, after interest has been lost to something else

    • Preferential technique: 2 stimuli are shown at the same time, measures preference for one over the other

    • Pattern perception: By 2 months, infants prefer patterned to plain stimuli, due to contrast sensitivity. As the infant grows, they will grow to keep preferring complex

    • Face-like stimuli: Newborn prefer to look at faces directly, infants like faces and face-like stimuli. This is more preferential for a parent, or stereotypical ‘attractive’ faces

    • Conspec: The perceptual characteristics of a face, 3 dots, argued that there is an innate recognition for this to help babies evolutionarily, under debate if it is innate or based on contrast

    • Perceptual narrowing: The decreased ability to discriminate between categories not present in one’s environment. The idea that things exposed to have an increased ability to pick out complexity, socialization essentially, expertise for what is environmentally relevant

    • Other-species effect: Perceptual narrowing that makes humans lose the ability to distinguish between the faces of other species. 6 months old don’t have this, but 9 to 12 months do

    • Other-race effect: Perceptual narrowing, happens to infants in homogenous environment, when surrounded by one race it is harder to make out individual faces of another race

    • Visual cliff studies: Reveals the link between crawling and depth perception, a plexiglass covered table creates an illusion that there is a ‘shallow’ and ‘deep’ side, where it looks like there is a cliff but there isn’t actually a cliff (for safety). Shows that the fear of heights isn’t innate, as young infants don’t mind the depth, but once crawling for a month, they do

    • Complex tones: Preferred to listen to by infants over more simple sounds, includes human speech

    • Positive affect speech: ‘Baby talk’, happy and intonated speech directed towards infants, preferred by infants

    • Statistical learning: Picking up statistically predictable patterns from the environment, relevant to speech as it shows pattern learning at 7-9 months where speech is broken into word-like units

    • Sweet flavors: Makes infants relax, applies to taste and odor

    • Sour flavors: Makes infants purse lips, applies to taste and odor

    • Bitter flavors: Makes infants form a distinct arch-like mouth opening, applies to taste and odor

    • Salty flavors: Early infants don’t enjoy these, though it is more tolerated at 4 months, applies to taste and odor

    • Touch sensitivity: Follows the homunculus, how perceptive particular areas of the body are to physical stimulus, super important to emotional learning

    • Pain sense: Well developed at birth, can be relieved by physical touch which releases endorphins and encourages soothing behavior and emotional comfort

  • Adults can see objects 600 feet away about as well as an infant can see objects 20 feet away, infants have much lower visual acuity

  • If habituation is tested with preferential looking, immediate habituation will occur where they stare at a family member’s face. If immediately tested, the infant will prefer a novel face over their family’s face, due to novelty. If instead there is a delayed test, dishabituation will occur and the infant will instead prefer to look at the family member’s face, due to familiarity. The amount of time this takes varies based on task and infant.

  • Infants prefer to listen to speech that is of the same language they are familiar with, they are able to distinguish between syllables and simple sounds. Over the first year, they tune into the native language and lose the ability to distinguish between foreign languages

  • During infancy, vision rapidly improves.

    • 2 months: Visual attention can be focused and scanning can occur

    • 2-4 months: color vision emerges rapidly, full by 4 months

    • 4 months: The ability to track moving objects is developed

    • 6 months: Visual acuity is 20/80, continues to develop

    • 6-7 months: There is depth perception developed

  • At 2-4 months, infants can distinguish different aspects of a face. Infants also prefer to look at faces of the same sex as their primary caregivers

  • Infants show preferences for sweet things or other things their parent ate during pregnancy, they can also make out their mother based on scent

  • Infants learn a lot about the environment through touch, particularly with the mouth, hand exploration increases at 4 months, actions become distinguished based on the object as development continues