1
Q
What is Sensation?
A
- It is often identified as involving simple “elementary” processes that occur right at the beginning of a sensory system, as when light stimulates receptors in the eye.
- Involves detecting elementary properties of a stimulus (Carlson, 2010)
2
Q
What is Perception?
A
- Complex process that involves higher-order mechanisms such as interpretation and memory that involve activity in the brain.
- Involves the higher brain functions involved in interpreting events and objects (Myers, 2004).
3
Q
The Perceptual Process
A
- Stimulus in the environment
- Light is reflected and focused
- Receptor processes
- Neural processing
- Perception
- Recognition
- Action
Perception and Recognition are interchangable. As well as Action and Recognition.
4
Q
Distal & Proximal Stimulus (Step 1of Perceptual Process)
Stimulus in the Environment
A
- The 1st step occurs when the individual observes the distal stimulus. (distal stimulus is a stimulus that is out in the environment).
5
Q
Distal & Proximal Stimulus (Step 2 of Perceptual Process)
Light is Reflected & Focused
A
- Light reflects from the stimulus, initiating the principle of transformation.
- The principle of transformation involves the conversion of stimuli and responses between the distal stimulus and perception.
- The first transformation occurs when light hits the stimulus and reflects into the eyes.
- Light entering the eyes undergoes transformation as it is focused by the cornea and lens.
- The image on the retina is the proximal stimulus , which is a stimulus in proximity to the receptors.
- The fact that the image is on the retina is the principle of representation.
- The principle of representation asserts that perceived experiences are based on the representation of stimuli formed on the receptors.
6
Q
Transduction (Step 3 of Perceptual Process)
Receptor Processes
A
- Visual receptors at the back of the eye receive reflected light from stimuli.
- These receptors transform environmental energy into electrical energy, shaping perception based on their response to various stimulus properties.
- The conversion of light energy to electrical energy is known as transduction.
- Transduction is crucial, ensuring information about stimulus representation reaches the brain, enabling perception to occur.
- Visual pigments influence perception by detecting dim light, and their effectiveness depends on the concentration and types of light-sensitive pigments in receptors across the visible spectrum.
7
Q
Step 4 of Perceptual Process
Neural Processing
A
- Ganglion cells, amacrine cells, bipolar cells, horizontal cells, rods and cone receptors create neural circuits (interconnected groups of neurons) within the retina.
- Signals generated in the receptors travel to the bipolar cells and then to the ganglion cells.
- The ganglion axons transmit signals out of the retina to the optic nerve.
- The electrical signals travel through a maze of neurons that transmit signals from the receptors to the brain as well as within the brain.
8
Q
Experience & Action (Steps 5-7 of Perceptual Process)
Behavioral Responses
A
- Electrical signals are transformed into conscious experience: the individual perceives the stimulus and recognizes it. Recognition occurs when an object is placed in a category giving it meaning.
- The final behavioral response is action which involves motor activities. The inidividual may decide to engage directly with the stimulus or observe it.
9
Q
What is the role of knowledge in the perceptual process?
Knowledge
A
- Knowledge includes information individuals bring to a situation.
- Acquired knowledge can be from the distant past or more recent experiences.
- Information acquired many years ago significantly affects one’s ability to categorize.
- When labeling objects, individuals categorize them based on knowledge learned during early childhood.
- These categories become an integral part of the individual’s knowledge base.
- Bottom-up processing: based on the stimuli reaching the receptors.
- Top-down processing: processing that is based on knowledge.
10
Q
Bottom-up Processing
A
- Also known as data-based processing.
- Example: When an individual does blind taste testing. They can probably guess that they are eating food or have other clues about what they are going to put in their mouth. But, they must use bottom-up processing to assess what they are eating. The brain assists the taste buds with this as they send sensory information to the brain and the brain has to do the work to figure out what the person just ate.
11
Q
Top-up Processing
A
- Also called knowledge- based processing
- Example: Observing the phase M~RY H~D ~ L~TTL~ L~MB and being able to decipher it due to your knowledge of English words, how words are strung together to form sentences and your famililarity with the nursery rhyme.
12
Q
Studying the Perceptual Process
Stimulus-Perception Relationship
This relates to steps 1-2 to steps 5-7
A
- This was the main relatinship measures before physiological methods became widely available.
- Oblique effect explored with black and white striped gratings.
- Grating acuity measured by presenting progressively thinner lines.
- Subjects indicate grating orientation to determine acuity.
- The smallest line width with correct orientation signifies grating acuity.
- When grating acuity is determined for different orientations, the acuity is best for gratings oriented vertically or horizontally.
Obliqe effect: people see vertical/horizontal lines better than random.
Diagram is Figure 1.10 on page 11 in Goldstein text.
13
Q
Studying the Perceptual Process
Stimulus-Physiology Relationship
This relates to steps 1-2 and steps 3-4
A
- Coppola et al (1998) measured the oblique effecr physiologically by presenting lines with different orientations.
- They measured ferrets’ brain activity using optical brain imaging that measures brain activity over a large area of their visual cortex and found that horizontal/vertical orientations caused larger brain responses than oblique orientations.
Diagram is Figure 1.12 on page 12 in Goldstein text.
14
Q
Studying the Perceptual Process
Physiology-Perception Relationship
This relates to steps 3-4 and steps 5-7
A
- Researchers determined this relationship for different line orientations by measuring the brain response and behavioral sensitivity in the same subjects.
- The behavioral measurements were made by decreasing the intensity difference between lighta nd dark bars of a grating until the subject could no longer detect the grating’s orientation.
- Subjects of this research were able to detect horizontal (90°) and vertical (0°) orientations at smaller light-dark differences than for the oblique orientations (45° and 135°)
Diagram is Figure 1.13 on page 12 in Goldstein text.
PSYC 2016
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Decks in class (4)
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