Humans have a predisposition to put random things into patterns. This phenomenon is called pareidolia; It means that we impose
patterns on random stimuli. Faces in cliffs, in clouds, in toast; we see things and assign something to nothing.
Sensation and Perception
Sensation; our sense organ’s detection of , and response to, external stimulus energy. Seeing takes place in the brain.
Perception; the brain’s processing of detected signals that results in intern representations of stimuli.
Can you have one without the other?
Yes. An example of this is the phantom limb; many people who have amputations may still be able to perceive their
limbs, and even have pain in these limbs. Even babies who are born without a limb, have a basic matrix in their brain
that knows where their limbs should be. Therefore, it gets stimulated by other things. Phantom limbs sometimes go
away, other times they do not. Sensation is a separable process, evidently. When you sense something, but don’t
perceive it, this is also possible, and common; the feeling of sitting in a chair, for example, because you are focused
on a lecture.
There are sets of steps that happen before the info gets where it needs to be.
Stimulus —> Sensation —> Sensory Coding —> Perception
Green light —> Seeing this —> Think about it —> React to it
Step One: The Stimulus
What is detected? What are the properties of the environment that are detected? Specifically timed
receptors pick up certain wave lengths.
Step Two: Sensation (Detection and transduction of the stimulus into neural imposes)
What is the sensory organ? Within the sensory organ, what are receptors? How is energy traduced into
mural impulses? For example, eyes and colour. Lightwaves activate in cones in different patterns, and
the processing within the retina. It then reacts and creates a chemical impulse, and then transferred t
the neural impulse. Coding in the retina is a matter of how the light is falling on the cell, what cell it is
falling on, and where it is coming from. For example, the afterimages of certain images in which it then
looks colour correct; these colour-after images. You fatigue the retina, and then when you go to the
white screen you get the rebound effect of the other tones.
Step Three: Transmission (Impulses travel to the primary cortical area for processing)
What is the pathway? For vision, we have to somehow blend together our two eyes that see slightly
different images, and put it all together. Hw is sensory info processed in the brain? Is it one part, or
multiple parts; 32 parts of your brain process this. Where is the info processed? Depends on what you
are looking at. Visual fields don’t correspond to eyeballs; if you lost an eye, you would be missing parts
of both visual fields. Info from one side goes up to the brain, and the other side stays.
Step Four: Translation (Reception of impulses)
We then have to translate the neural impulses, and translated them into information, so that we can put
it together. Where does the info go? All sensory systems go through the midbrain, and then is sent off.
What part of the brain processes the info? When you have a mental representation of something, that
metal representation or image in our head,s has to be put back together by the bits of info send by our
retinas. The frontal lobe, the parietal lobe, the temporal lobe, and the occipital lobe are all important
factors of our brain and our images. It also all has to go through the thalamus.
Step Five: Perception and Attention
Did you register the input? The threshold of the lowest level of light is different for everybody. A point
just above that is when you start to see things. Did you “see” or "hear” or "feel” the stimulus? It is a
different question to ask what did you see, hear, or feel. It is more than picking up the information, its
an active construction.
Somehow your brain does magic, and we don’t understand how it works.The brain takes things apart; processing
form, colour, movement, sound, and the like all separately in the brain, but we put them together, and we have a
representation of it. If you have brain damage in a certain part of the brain, your reality is gone, because your
perception is gone. When we reach for something, we form a hand to pick things up. Some people are not able to
identify a water bottle, but can pick it up, and others can identify it, but cannot pick it up, because of damage to their
action-visual part of their brain.
Humans have a liking for faces; we are able to better remember faces than objects. When shown faces, the bran lights up on
the right hemisphere on our brain, especially. People who have damage to their brains there have difficulty recognizing
people by faces. We have a special area in our brain evidently that process just faces.
Optical illusion work on the brain because of how we view things. We perceive things differently with different angles.
Forming the conscious percept
Botom up versus top down processing.
A Bottom Up Approach
This means they start with the smallest bit and build up. It puts single elements together to construct a
whole. For a long time, this was how we explained vision.
Simple cells in visual context (V1). In the first place in the brain that the visual went to, they labelled
them as simple cells, because they found one to one contact with the cells and the retina. It meant that
there was now a way for the bits and pieces of info to get to the brain.
Top Down Processing
Gestalt psychology (started in Germany) in which pyschophyics just started out with. It put together
physics with psychology “the whole is different from the sum of the parts”. They recognize that our
brain does patterns.
It imposes patterns on fragmentary information; the brain recognizes whole patterns from fragmentary
info. We develop this through experience and learning how to perceive things.
Evolved predispositions and learned context help us with this.
Examples of Gestalt Principles
The closer two figures are to each other, the more likely we are to group them and see them as a part of the same
We tend to group figures according to how closely they resemble each other
We tend to interpret intersecting lines as continuous
We tend to complete the figure even when the gaps exist
We tend to perceive contour even when they don’t exist
Your brain creates a reality for you.
Humans have a predisposition to put random things into patterns. This phenomenon is called pareidolia; it means that we impose patterns on random stimuli. Faces in cliffs, in clouds, in toast; we see things and assign something to nothing. Sensation; our sense organ"s detection of , and response to, external stimulus energy. Perception; the brain"s processing of detected signals that results in intern representations of stimuli. An example of this is the phantom limb; many people who have amputations may still be able to perceive their limbs, and even have pain in these limbs. Even babies who are born without a limb, have a basic matrix in their brain that knows where their limbs should be. Phantom limbs sometimes go away, other times they do not. When you sense something, but don"t perceive it, this is also possible, and common; the feeling of sitting in a chair, for example, because you are focused on a lecture.