what is sensation?
information about the environment picked up by sensory receptors and transmitted to the brain.
what is perception?
the brain’s interpretation of this input, how we understand the events, objects and people in our environment.
what are the three aspects of visual perception development?
visual acuity, visual scanning and colour vision.
how does visual acuity develop through infancy?
visual acuity is poor at birth and increases rapidly int he first 6 months, reaching almost adult levels by 1 year old.
how is visual acuity tested in infants?
multiple panels with black and white lines are held in front of babies to see if they can see the lines or just one big blob of colour.
how does visual scanning develop throughout infancy?
while babies are younger than 2 months they cannot track moving objects smoothly, this develops as they get older. at 1 month old babies will focus on limited features of a shape, particularly the outside edges. by 2 months they will start to focus on internal features of shapes.
how does colour vision develop throughout infancy?
newborns can distinguish between different bold colours e.g. red and white, but not between colours that are more similar. at around 1 month they look longer at the brighter, bolder colours and by 4 months they are close to adult ability.
what are the three main ays of testing perceptual abilities?
preference tests, habituation tests and conditioning.
what are preference tests?
two stimuli are presented to an infant at the same time, the length of time they look at each is recorded. if they have a preference for on over the other, ie look at it longer, it shows us that they can see a difference between the two.
what did Fantz (1961) find in their preferences tests?
infants spend more time looking at more complex images than simpler images.
what is a habituation test?
show an infant an image over and over again until they get used to it and they lose attention then show a different image of a ‘scary clown’ and if they can tell the difference they will regain interest (dishabituation). tells us they can distinguish between the two.
what is conditioning?
can get dummies that record the rate at which the baby is sucking them, this shows if there is any difference in sucking rate when presented with different stimuli. if there is a difference this shows they can distinguish between the two.
why is facial perception useful?
you can tell; species, sex, race, identity, mood, emotional state, intent, truthfulness from a face. some of these are subconscious. this means face perception has a big impact on social interactions.
what is the nature vs nurture debate in terms of facial perception?
nativism - abilities from birth, innate or inborn.
empiricism - acquire over time through experience, learned.
it’s not really a debate of one or the other but rather how big a role is played by each.
what did Fantz (1961) find about 1-15 week old’s innate face preference?
by showing three panels, one with a face, one with all the features of a face int he wrong places and one just with the dark at the top and light at the bottom; Fantz found that babies looked at both the first for the same length of time suggesting it’s not a face preference but rather a preference for complexity.
what did Maurer and Herrera (1981) find about innate face preference?
they used three panels, one with a schematic face and the others the same level of complexity but the features all in the wrong places. found that by 2 months babies were looking longer at the schematic face suggesting that face preference is predominantly nurture. we have a natural interest in complexity but experiences are what show us to be more interested in faces.
what did Goren et al (1975) find about innate face preference?
used moving stimuli as this is more realistic and found that newborns tracked the schematic face more than the other two.
what did Johnson et al (1991) find about early face preference?
they replicated the experiment with newborns and 3 month olds and found that by 3 months they no longer tracked the face more, left the question of why the face preference vanished.
what is Johnson and Morton’s (1991) 2 process model?
conspec - an early system (subcortical structures) biases infants to look at faces while conlearn - a more mature system (visual cortex) which takes over and has more precise recognition.
what else can newborns do?
recognise identity of novel individuals, recognise eye-gaze - theuy look more at direct eye contact than pictures of people who are looking up/dow/to the side, recognise expressions, prefer faces declared attractive by adults, discriminate mother’s face - sucking rate increases when mother’s face shown.
doesn’t necessarily mean it is innate because newborns are often exposed to a lot of faces very quickly.
what did Pascalis et al (1995) find about newborn’s preference for their mother’s face?
the preference disappeared when the outside of the face and the hairline was masked, suggests newborns use outer features to identify faces.
what Turati et al (2006) find about newborn’s preference for their mother’s face?
found that newborn’s could use both inner and outer features to identify their mother’s face but they struggled more when the outer features were removed than when the inner features where removed. suggests they use the outer features more than the inner features to identify faces.
is face perception innate to some extent?
Sugita (2009) found that monkeys not exposed to faces for the first months of life still preferred them when exposed to them, this study could be questioned as they could not see any faces but they could feel their own face, we know how strong the connection between senses is so this could still count as exposure to faces.
why can babies distinguish between different primate’s faces and adults can’t?
babies have 1 ½ times the number of synapses as adults, this gives them skills they will never need such as recognising the differences in primate faces, this means we lose these skills as we grow up because we are only really exposed to human faces.
