Dr Kevin Paterson

1

• Topics
• The visual systemDepth perception
• Using visual illusions to study vision.
• Ecological approaches to vision

• Dr Kevin Paterson
• k.b.paterson_at_derby.ac.uk
• Essential reading
• Eysenck, M. W., Keane M. T. (2001). Cognitive
  psychology. Psychology Press Hove, UK.

2

• FUNCTION OF EYE
• Light is reflected from surface of objects. It
  passes through pupil lens before landing on
  retina at the back of the eye.
• The optic nerve passes neural data to the
  mid-brain. This passes information onto the
  visual cortex.
• Visual data is processed at the retina, by areas
  of the mid-brain, and regions of the visual
  cortex.

3

• BOTTOM-UP TOP-DOWN PROCESSES
• Major debate is vision predominantly a bottom-up
  or top-down process?
• Bottom-up sensory information is processed in
  terms of basic features, features are combined to
  form objects, and objects are recognised.
  Perceiver reconstructs objects in world.
• Top-down perceiver uses knowledge and
  expectations to impose interpretation on incoming
  sensory data. Perceiver hypothesises about
  objects in world.

4
LIGHT

• RETINAL STRUCTURES
• Light passes through neural layers strikes
  receptors (rods cones). Cones concentrate in
  fovea, none in perifovea.
• Neural signal passes to bipolar cells then
  ganglion cells.
• Ganglion cells specialised for detection of
  particular patterns of light falling on the
  retina.

5

• VISUAL PATHWAYS
• Neural pathways take information from retina to
  Lateral Geniculate Nuclei (LGN) to visual cortex.
• Optic nerve for each eye splits with half going
  to right side of brain and half to left side of
  brain.
• Pathways Parvocellular involved in colour vision
  focal attention. Magnocellular involved in
  non-colour vision and global attention.

6

• VISUAL CORTEX
• Neurons within the visual cortex as specialised
  for feature detection, lines of particular
  orientation.
• P- and M-pathways extend into the visual cortex.
• Parvocellular neurons are specialised for
  processing of detailed visual information.
• Magnocellular neurons are specialised for
  processing of novel or moving stimuli.

7

• Visual illusions - what they tell us about
  perception

8

• Visual illusions - what they tell us about
  perception

9

• Optic flow

10

• Motion parallax

11

• Muller-Lyer illusion

12

• Muller-Lyer illusion

13

• Motion parallax