Lecture 5 – Visual Perception: Context and Theories
Last Class: Sensation versus Perception
Sensation –
o
Occurs in the sensory organs.
o
Energy from a physical stimulus in the environment that is picked up by sense
organs.
Light, sound, smell, etc.
Translates this into some sort of neural impulse or signal.
Perception –
o
Follows sensation.
o
When the brain organizes sensed information (organizes those impulses), and
translates it/interprets it as something meaningful.
Perception – understanding what is around us.
McGurk Effect and the Brain
We talked about how different senses might interact…
People perceive speech as what they see…
Compared brain activity for people who experienced the McGurk effect and those people
who did not experience this effect.
The left superior temporal sulcus is important for audiovisual integration during speech
perception.
o
More active for people who experienced the McGurk effect.
Region is important for integrating senses – so if it is activated more,
coupling audiovisual information more tightly that someone who is less
susceptible – more influenced by the McGurk effect.
Underlying neuromechanisms for this effect.
o
Individual differences are seen in the brain!
How we take in information is represented in the brain.
From the Eyes…
Early visual system –
o
Step 1 – Light waves enter the eye and are focused on the retina, a thin layer of
tissue at the back of the eye.
o
Step 2 – Photoreceptors in the retina (rods and cones) convert light to electrical
activity.
Rods – dim light visions.
Cones – colour and detail.
o
Step 3 – This electrical signal is sent to bipolar cells then onto ganglion cells.
