Lecture 1 - Perception Flashcards
Sensation Definition
Information about environment picked up by sensory receptors and transmitted to brain
Perception Definition
Interpretation by the brain of this input (how we understand the events, objects and people in our environment)
Visual Acuity Definition
Ability to process fine detail
When does visual acuity develop?
Poor at birth, rapid increase in first 6 months.
Near adult levels by 1 year
Visual Scanning Definition
The ability to track objects
When does visual scanning develop?
Younger than 2 months, cannot track moving objects smoothly
1 month – focus on limited features of shape, particularly outside edges
2 months: start to focus on internal features
When does colour vision develop?
Newborns can distinguish between white and red, but not other colours (ex: Adams et al. 1994)
Around 1 month, look longer at brighter, bold colours
By 4 months close to adult ability
What is a preference test?
Present two stimuli at the same time and measure how long an infant looks at each.
Franz (1961)
Infants spend more time looking at a face, but enjoy more complex shapes too.
1-15 week old babies prefer a more complex pattern, face or not.
What are habituation tasks?
Shown interesting stimulus repeatedly so child loses interest, change to a different stimulus so infant has renewed interest and looks again (dishabituation) – this sees if infant can tell the difference between stimuli
What are conditioning tasks?
Repeatedly reward target behaviour (like increased sucking rate). Infant becomes habituated to stimulus. Stimulus is altered – if infant does not increase sucking rate treats 2 stimuli as the same, if not can tell the difference.
Face perception quote (Moulson et al, 2009)
“Faces are arguably the most important visual stimulus used in human social communication”
Why is face perception useful?
What can you tell from a face? (species, sex, race, identity, mood, intent)
Crucial ability for successful social life.
Maurer and Barrera (1981)
At 1 month there was no difference in looking times and at 2 months they preferred to look at a neutral face.
Goren et al (1975)
Used moving stimuli instead of static and found newborns track schematic face more than complex patterns/blank shape.
Johnson et al (1991)
Replicated Goren et al study and found that after 3 months they no longer track more
2 Process Model researchers
Johnson and Morton (1991)
2 Process Model parts
CONSPEC – early system (subcortical structures) biases infants towards faces, CONLEARN – later taken over by more mature system (visual cortex) and more precise recognition