PSYC 1200 Lecture 3a
Chapter 4: Becoming Aware of What’s Out There
Sensation Process of receiving information from the external and internal world.
Stimulation of sense organs
e.g. pain, hunger, light waves, sound waves
Perception To impose a meaningful interpretation on the information sensation provides.
We perceive a version of what reality might be, but it can deviate from actual reality
Selection, organization and interpretation of sensory input
Process of 1. Sensory organs absorb energy from stimuli in the environment.
Sensation and 2. Sensory receptors convert stimulus energies into neural impulses, which are sent to the brain.
Perception 3. Perception is the brain organizes this input and translates it into something meaningful.
Muller Lyer Illusion If two objects project the same size image on your retina, the one perceived as further away will be perceived as
The corners of square buildings have angles/arrowheads at the top either facing down when the corner is coming
towards you or facing up where the corners are going away from you.
Societies without these square buildings do not develop Muller Lyer Illusions.
Visual Contrast Two colors that are exactly the same, but appear in different backgrounds, appear to have different brightness.
Effect Perception operates by the relative color of brightness according to the darkness of the background it’s encountered
in; darker background makes a color appear brighter.
Ponzo Illusion The top line appears longer
When lines converge, it indicates that something is further away.
When two objects have the same retinal size, whichever one is perceived as further away is perceived as larger.
Poggendorff Illusion The two lines appear not lined up, but they do line up exactly if you line them up with a ruler.
Upside-down T The vertical line appears longer than the horizontal line, but they are the same length.
Since the vertical line bisects (divides) the horizontal line, we perceive the horizontal line to be shorter.
Zollner Illusion It appears that the lines are not parallel, but they are. The other bars cutting into the lines give the illusion that they
Impossible Figures Figures that cannot exist because they do not make sense.
When you give a person a stimulus that is difficult to understand, you start to feel the perceptual processes that work.
Sense Organs Eyes for seeing; tongue for tasting; nose for smelling; ears for hearing and balance; skin for touching/sensing
heat/pain; muscles for sensing body movement.
Sense Receptors Each person has receptors specialized for each type of input that converts sensory information into neural signals that
the brain can interpret.
Johannes Muller Suggested the Doctrine of Specific Nerve Energies:
(1926) People experience different types of sensations because sense organs send signals to different parts of the brain.
Doctrine of Specific Explains how different sensory modalities are perceived differently, but does not explain different types of perception
Nerve Energies within the same modality (e.g. loud vs. quiet; red vs. blue; bitter vs. sweet).
These patterns are explained by patterns of neural messages within a specific brain area.
Synaesthesia Stimulation of one sensory modality evokes sensation in another modality.
e.g. colors associated with seeing numbers, taste or smell associated with an experience.
Chapter 4: Sensation and Perception 1 PSYC 1200 Lecture 3a
Chapter 4: Vision
Vision The basis for sight is light energy which reflects off objects and surfaces and travels in waves.
Characteristics of these waves affect 3 psychological dimensions of our visual world: hue, brightness, saturation.
Hue/color Wavelength of light energy leads to perception of hue/color.
Everything we see and perceive is based on the reflection of light off of objects. Light strikes objects, bounces off it
and slams into the back of our retina, which allows us to perceive visual information.
Longer Wavelengths = orange/red = 660 nm and up
Shorter Wavelengths = violet/blue = 470 nm and below
All Wavelengths Combined = white
Brightness Amplitude of light energy leads to perception of brightness/intensity.
The more light is reflected by an object, the brighter it appears.
Saturation Involves the range of wavelengths reflected.
Single Wavelength = pure light = colour is vivid and described as highly saturated.
Multiple Wavelengths = complex light = colour is dull and described as low in saturation.
e.g. Bright red is highly saturated because it mainly consists of red wavelengths. Pink is low in saturation because it
is mixed in with red wavelengths and other wavelengths.
Additive Mixing Mixing light is additive because you are adding in different wavelengths. All wavelengths combined make white light.
Subtractive Mixing Mixing paint is subtractive because paints have pigments in them which capture some of the wavelengths. If
wavelengths are being captured, they are not being reflected out, so they do not reach your eye and you see black.
Cornea Front of the eye that is rounded and transparent to help bend light towards the lens.
Lens Can be made fat/curved (light bends a lot) or skinny (light bends a little).
Fat lens is for bringing close objects into focus.
Skinny lens is for bringing far objects into focus.
As a person ages their lenses become less flexible.
Near-sightedness The lens improperly focuses the light and bends it too soon
Focus point falls in front of retina.
Far-sightedness The lens does not bend the light enough.
Focus point falls behind the retina.
Iris Controls how much light enters the eye through the pupil.
If bright outside, iris constricts letting less light in; also indicates that you are bored.