Development of Perception

1. Development of Perception • Describe some methods used to investigate infants. • Describe some studies into the development of depth perception and use them to decide if it is innate. • Research some studies into the development of visual constancies and use them to decide if it is innate. Nature/Nurture debate: are our perceptual abilities inborn/innate or developed through Learning and experience?

2. How do you know what I am thinking?

3. Preferential Looking

4. Habituation

5. Sucking rate

6. Conditioning + + +

7. Heart and breathing rate

8. Positron emission tomography andFunctional magnetic resonance imaging

9. Development of Perception • Describe some methods used to investigate infants. • Describe some studies into the development of depth perception and use them to decide if it is innate. • Research some studies into the development of visual constancies and use them to decide if it is innate.

10. Development of Perceptual Abilities How far away is that bottle? Is depth perception learned or innate? Development of depth/ distance perception.

11. Depth Perception • How do we know what we see is 3d if the image falling on the retina is flat and 2D? • -Bottom up-Gibson, visual cues such as texture gradient picked up from the optic flow. • -Top down- Gregory, visual cues are learned through past experience.

12. Binocular depth cues Retinal disparities- the closer an object is to the viewer the more different the images from the two eyes will be. Occular Convergence – How ‘crossed’ your eyes are when you look at something. Monocular Dynamic e.g. motion parallax (as we move objects that are closer to us appear to move more quickly than objects in the distance) Static (pictorial) e.g. relative size, texture gradient, linear perspective, occlusion, overlap.

13. Gibson and Walk (1960) http://www.vimeo.com/77934 Most infants aged 6 months would not crawl to their mothers. This was true even if they had a patch over one of their eyes. This indicates that they are using binocular and monocular depth cues even at this young age! Gibson and Walk used this, and the fact that day old chicks and goats avoided the cliff to suggest that depth perception is innate.

14. HANG ON!! • Innate? That’s the whole nature nurture debate?! • 6 months?! How can they say it is innate, by this time they are already moving around, crawling etc. How can we tell they didn’t LEARN it? • Even earlier would be better evidence.

15. Visual Cliff • Campos et al (1978) placed a two month old infants on the deep side of the visual cliff and found that their heart rate was slower than when on the shallow side- a slower heart rate indicates interest. This suggests that they could distinguish between the two sides are were able to perceive depth.

16. Motion parallax- Hofsten et al (1992) • Found evidence for motion parallax in infants at 3 months old using a habituation technique.

17. Hofsten et al (1992) • Habituation technique showed they treated this as a novel stimulus. • 3 months old- they thought they had seen this! MUST be down to motion parallax.

18. Preferential reaching 7 months old reach for the ‘closer’ object, whereas 5 months old do not. Nature nurture?!

19. Infant DevelopmentDepth and Distance Research Yonas et al (2001) tested whether infants use shadows as a cue to depth. Infants were shown 2 toys, both equidistant from them but one appeared to be closer because of added shadows. The infants also had one eye covered to remove binocular information for depth. Older infants (30 weeks) were more likely to reach towards the apparently closer toy than younger infants (21 weeks), suggesting that the ability to use shadows as a cue to depth develops with age.

20. BUT………….. • At 2 weeks old Bower et al (1970) found that neonates shielded their eyes at approaching objects, suggesting perception is innate. This is MORE scary, even though the two cubes are the same retinal size……… Bower, Broughton and Moore (1970)

21. Development of Perception • Describe some methods used to investigate infants. • Describe some studies into the development of depth perception and use them to decide if it is innate. • Research some studies into the development of visual constancies and use them to decide if it is innate.

22. Development of Perceptual Constancies

23. Perceptual constancies • Bower 1966 (two studies- cubes and trapeziums) • Slater et al 1985 • Ghim 1990 • Melzoff (faces) • There must be more recent ones! • http://www.artsci.wustl.edu/~sshale/Chapter-5.pdf

24. What evidence do we have that perceptual abilities are Nature or Nurture? Bottom up? Top down?

25. Problems studying nature/Nurture in infants • An infant has experiences in the womb amd may learn some sensorimotor processes • Some innate abilities only show when the nervous system is mature • All the techniques rely on assumptions • Investigator bias

26. Development of Perception • Describe some methods used to investigate infants. • Describe some studies into the development of depth perception and use them to decide if it is innate. • Research some studies into the development of visual constancies and use them to decide if it is innate.