Psychology Chapter on Sensation and Perception

Weber's Law

• Just noticeable difference (JND) is proportional to initial stimulus intensity, not a constant amount.

Perception

• A constructive process creating meaningful situations from presented stimuli.

Top-Down vs. Bottom-Up Processing

• Top-down: Perception guided by higher-level knowledge, experience, expectations, and motivations.
• Bottom-up: Perception progresses from individual stimulus components to the whole.
• Example: Ability to read text even with jumbled letters (except first and last) demonstrates top-down processing; the brain interprets the word as a whole, not individual letters.

Sensation vs. Perception

• Sensation is the physical aspect of sensory input.
• Perception is the psychological interpretation of sensory input.

Sensory Adaptation

• Decline in sensitivity to unchanging stimuli due to sensory nerve receptor limitations.
• Receptors are highly responsive to changes in stimulation.

Factors Affecting Perception

• Sensory adaptation: adjustment in sensory capacity after prolonged unchanging stimuli.
• Attention: Inattentional blindness – failure to notice visible objects due to lack of attention (illustrated with video examples).
• Motivation: Our desires influence perception, such as believing we hear a phone ring when we're expecting a call. Signal detection theory highlights this.
• Beliefs, values, prejudices, and expectations: These shape our interpretations of stimuli, for example, preference rating for low-fat food.
• Life/cultural experiences: Influence perceptual interpretations. Example: Individuals from Western cultures are more prone to certain visual illusions compared to those from non-Western cultures. Müller-Lyer illusion demonstrates differences.

Reaching the Retina

• Retina converts light's electromagnetic energy into electrical impulses for transmission to the brain.
• Contains rods (low-light vision) and cones (sharp focus, color perception).

Rods and Cones

• Basic eye cells. Light travels through ganglion and bipolar cells before reaching rods and cones.
• Rods and cones transmit nerve impulses via bipolar and ganglion cells to the brain.

Sending the Message from the Eye to the Brain

• Optic nerve carries visual information to the brain.
• Optic nerve passes through the retina creating a blind spot (lack of rods and cones).

Explaining Color Vision

• Trichromatic theory: Three types of cones (blue-violet, green, yellow-red) in the retina, each sensitive to a specific wavelength range.

Cochlear Implants

• Information available through indicated links.

Taste

• Four basic tastes: sweet, sour, salty, bitter.
• Umami (amino acids) is a fifth category.
• Taste buds (approx. 10,000) are replaced every 10 days.
• "Supertasters" have high taste sensitivity, while "nontasters" have low sensitivity.

Smell (Olfaction)

• Detects over 10,000 smells.
• Strong link to memory.
• Olfactory cells in nasal passages are the receptor neurons for smell.
• Pheromones are chemicals involved in social communication.

Skin Senses: Touch, Pressure, Temperature, and Pain

• Nerve receptor cells at varying skin depths detect touch, pressure, temperature, and pain.
• Pain has physical and psychological components.
• Substance P transmits pain messages to the brain.
• Emotions and thoughts also significantly affect pain experience.
• Skin sensitivity varies; fingertips are particularly sensitive.

Gate-Control Theory of Pain

• Specific nerve receptors in the spinal cord activate a "gate" to the brain related to pain.
• Other receptors can close the gate, reducing pain through competing stimuli, psychological factors, and cultural influences.
• Distinction between inflammatory and neuropathic pain.

Gestalt Laws of Organization

• Principles describing how we organize information into meaningful wholes.
• Closure: We perceive complete figures even with missing parts.
• Proximity: Elements closer together are perceived as grouped.
• Similarity: Similar elements are seen as grouped.
• Simplicity: We interpret patterns in the most straightforward way possible.

This quiz covers essential concepts in psychology related to sensation and perception, including Weber's Law and the differences between bottom-up and top-down processing. Explore how various factors affect our perception and the role of sensory adaptation in interpreting stimuli. Test your understanding of these fundamental ideas that shape our sensory experiences.