Chapter 4 - Introduction to Psychology

Sensation

the conversion of energy from the environment into a pattern of responses by the nervous system. The registration of information at the senses.

Perception

Making sense of the registered information -- occurs in the brain

Step 1 of Sensory Pathway

Environmental Stimuli

Step 2 of Sensory Pathway

Receptors (Transduction)

Step 3 of Sensory Pathway

Signal to the brain (Thalamus)

Step 4 of Sensory Pathway

Activates appropriate brain area

Step 5 of Sensory Pathway

Perception

1. Environmental Stimuli

Signals from an organism’s surroundings that influence how it acts or functions

2. Receptors (Transduction)

Specialized cells or nerve endings that detect specific types of environmental stimuli and initiate the process of transduction by converting these stimuli into electrical signals (nerve impulses)

3. Signal to the brain (Thalamus)

Electrical nerve impulses that travels from sensory receptors to the brain, where the signals are interpreted as sensations like sight, sound, touch, taste, or smell

4. Activates appropriate brain area

Directed to a specific part of the cerebral cortex that is specialized to interpret that type of sensory input

5. Perception

The brains interpretation of sensory signals, turning raw data (like light, sound, or pressure) into meaningful experiences

Transduction

When sensory receptors (like those in your eyes, ears, skin, etc.) convert environmental stimuli (light, sound, pressure, chemicals, etc.) into electrical nerve impulses

Cornea

Focuses the light onto our visual receptors. Rigid.

Lens

Focuses the light onto our visual receptors. Flexible and bends when focusing the light

Pupil

Surrounded by the Iris. Determines how much light is let in

Iris

Colored part of the eye. Determines how much light is let in

Bright light

Pupil constricts & reduces the amount of light

Dim light

Dilates and lets more light in

Aroused

pupils dialate

Vitreous Gel

Where light is sent back through. Provides the shape to the eyeball

Retina

Contains the visual receptors. Where transduction occurs

Visual Receptors

Rods & Cones

Fovea

Point of central focus. Important when we are trying to see things in fine detail

Blind Spot

Contains no visual receptors. Axons from the visual receptors (rods & cones) exit the eye here

Optic Nerve

Formed from the Blind Spot. Sends information to the brain. (Frist stop Thalamus, ends at Occipital Lobe)

Thalamus

Small but crucial structure located deep in the center of the brain. It acts as the brain’s main relay station for sensory information.

Occipital Lobe

The occipital lobe is the rearmost part of the cerebral cortex in the brain and is primarily responsible for processing visual information.

Cones

Used for daytime, color vision & fine details. There are 6 million cones in the retina, found mostly in & around the fovea. They respond most to colors & are used for acuity.

Rods

Used for night vision (120 million). Found in the periphery of the retina & do not respond to colors. They become active when the lights are turned off. There are no rods in the fovea!

Dark Adaptation (aka Purkinje Shift)

Switching from our cones to rods. During the daylight hours, we use our cones to see, while at night the cones aren't as effective. The rods kick in & take over. This is a gradual process which takes place as soon as lights are turned off. There is a gradual improvement in your ability to see in the dim light (as the rods become active). Ex. At the movies: You can't see when you first enter the theater - it takes between 10-20 minutes for the rods to completely adjust.

Presbyopia

"old eye" - while many of us will escape some of the visual problems - none of us are immune to this - it is a product of the aging process! The lens is a flexible structure, allowing us to keep our world in focus. As we age, the lens stiffens and is less flexible, impacting our ability to see, particularly items that are close to us. There is no cure, but may be corrected with glasses.

Color Blindness

Total color blindness is very rare! Most people can distinguish one color from another. About 4% of all people have some form of color blindness. The most common is Red/Green color blindness (trouble distinguishing red from green & red or green from yellow). Females are not usually colorblind - mostly occurs in males (R/G). Currently, there is no cure for color blindness.

Top-Down Processing

Perception guided by prior knowledge and experiences, influencing the interpretation of sensory information

Schemes

In top-down processing, perceptions are interpreted from individual frameworks that help us perceive and interpret information

Myopia

some people have eyeballs that are too long, which allows them to focus on close objects, but they can't focus on far objects - nearsightedness. May be corrected with contacts, glasses, or laser surgery

Hyperopia

the eyeball is too short or flattened - can't see near objects, but can see far objects - farsightedness. May be corrected with contacts, glasses, or laser surgery

Astigmatism

vision is blurred in some orientation due to a misshapen cornea. Use a fan chart to test for specific problems. Corrected with glasses.

Cataracts

lenses get cloudy - general problem in the elderly (@75% of people >65 have cataracts). Corrected by removing the lens and replacing with a contact lens.

Glaucoma

leading cause of blindness in the U.S. There is a small opening between the lens and the iris which allows the aqueous humor to flow through. Blockage of this opening occurs, preventing the fluid from flowing properly. This causes a build-up of the fluid, which in turn causes pressure, which is very painful. The pressure pushes the eyeball against the optic nerve, which kills the nerve fibers - resulting in blindness. There is no cure, but treatment includes eye drops, pills, laser procedures, and surgical operations such as an Iridectomy

Iridectomy

drill a hole in the iris which allows the fluid to flow and reduces pressure.

Macular Degeneration

Second leading cause of blindness in U.S. The macula surrounds the fovea and its purpose is to "nourish" the fovea. - if it degenerates, it causes a loss of your central vision. You are still able to see in your periphery however. Occurs mainly in older folks. There is no cure, but treatment may include glasses, surgery, medications, and change in diet.

Gestalt Psychology

"The whole is greater than the sum of its parts!" Gestalt means "form" or "configuration" in German. This explanation if built upon the thought that people naturally organize the perceptual field according to certain patterns. The Gestalt approach was introduced in 1912

Principle 1 of Gestalt Psychology

Figure-Ground (Reversible Figures)

Principle 2 of Gestalt Psychology

Proximity

Principle 3 of Gestalt Psychology

Similarity

Principle 4 of Gestalt Psychology

Good Continuation

Principle 5 of Gestalt Psychology

Closure

Figure-Ground

Our ability to distinguish objects from their background

Reversible Figures

ambiguous figures that are difficult to determine what is the figure and what is the background.

Similarity

tendency to perceive objects that are similar as a group/unit

Good Continuation

when figures are interrupted, we tend to fill in the interrupted area to make them "continue"

Closure

tendency to complete objects that are incomplete

Proximity

Tendency to perceive objects that are close together as belonging to a group/unit