PSY BEH 11A Lecture Notes - Lecture 11: Infante, Neuroglia, Prenatal Development
14 Nov 2018
School
Department
Course
Professor
Jessica Mangold
PsyBeh 11A
Professor Hoffman
Week 6 Lecture 1
11/6/18
Visual Development
Infant Vision
- what do they see?
- can they see color? Depth?
- do they recognize faces?
- problem: they can’t speak
- infans: Latin, can’t speak
- how can we find this out?
- experimental techniques
- results: first 15 months
Prenatal Development
- 10 weeks: cortical neurons start
- brain starts to be formed about 2 ½ months into pregnancy
- 18 weeks: they are fully formed
- migrate through the brain
- neurons have to physical move to where they need to be
- cells have to figure out where they have to go & who they have to be connected
to in synapses
- brain has various regions & layers
- many parts of cortex have 6 layers
- various regions of the brain perform different functions
- not all spelled out in the DNA where neurons have to go
- have algorithms programmed instead -> climb the glial cells
- follow chemical gradients created by genetics
- 2nd trimester: synapses start to form
- 6 months & following: synapses are pruned
- go through massive building up & then period of losing synapses as part
of development & learning
- learn as much by deleting synapses as you do by adding them
The Eye
- the neonate (baby when first born)
- about half the size of the adult
- big compared to rest of body
- 1 year: about ¾ adult length
*lots of attention given to eyes & vision during early stages of development
Experimental Techniques
- Forced Choice Preferential Looking
- infant: something > nothing
- infants prefer to look at something rather than nothing
- get bored very easily & want new stimulation all the time
- allows evaluation of what visual system is able to see
- can keep track of where infants looking -> can figure out whether they are seeing
anything
- acuity
- for adults -> have to read letters off of a chart
- used Forced Choice technique for children
- sine-wave grating, matched gray
- can find average luminance of grey in the sine-wave grate & then place that gray
to the side
- can show them fat or skinnier bars with the sine-wave grate
- will demonstrate how much contrast they see
- experiment to find out how good their acuity is
- vary spatial frequency
- fancy name for how fat the bars are
- if the bars are very skinny, then that means that go through lots of bars in small
region of space -> high spatial frequency
- low spatial frequency -> fatter bars
- judge eye gaze
- judge whether for each spatial frequency whether child is looking at side with
the grating vs the side with just the grey
- if eyes looking systematically at side with bars -> know they can detect that
spatial frequency
- use of double blind procedure
- researcher has no idea which side has the bars when making judgement about
child’s eye gaze
- if they look at the grating longer than at the pure gray side -> infer that the child’s visual
system can resolve those gratings
- have enough acuity to do that
- habituation
- babies easily get bored & want to look at new things rather than old things
- habituate to a new stimulus
- will look at something more if it is new rather than looking more at something
that is old
- frequency discrimination
- show the infant some bars & then show new set of bars that is slightly fatter or
thinner
- can determine whether it is a new stimulus or not
*innate desire to look at something that is more attractive can be confounding in
this experiment
- Preferential looking & look at what might surprise them
- infants tend to look at things that are unexpected more than things that they expect
- true for adults as well
- can be used to see about visual ability of children to count things
- 2 toys; curtain; add 1 toy
- child sits in front of a stage with curtain drawn
- put two toys on the stage
Document Summary
Neurons have to physical move to where they need to be. Cells have to figure out where they have to go & who they have to be connected to in synapses. Not all spelled out in the dna where neurons have to go. Have algorithms programmed instead -> climb the glial cells. *lots of attention given to eyes & vision during early stages of development. 6 months & following: synapses are pruned. Go through massive building up & then period of losing synapses as part of development & learning. Learn as much by deleting synapses as you do by adding them. Infants prefer to look at something rather than nothing. Get bored very easily & want new stimulation all the time. About half the size of the adult. Brain starts to be formed about 2 months into pregnancy. Many parts of cortex have 6 layers. Various regions of the brain perform different functions.
