Psychology Chapter on Perception

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Questions and Answers

What is the main function of rods in the human eye?

Sensitive to low light (correct)

Important for visual acuity

Responsible for color vision

Work best in bright light

What occurs during depolarization of a neuron?

Sodium ions rush out of the neuron

Sodium ions rush into the neuron (correct)

Voltage-gated sodium channels close

The membrane potential becomes negative

What is the typical resting membrane potential of a neuron?

-70 mV (correct)

-40 mV

-55 mV

+40 mV

What is the role of the sodium-potassium pump in neurons?

Maintains resting potential Signup and view all the answers

Which statement is true regarding the process of transduction in vision?

Rods and cones convert light into electrical signals Signup and view all the answers

What must be reached to trigger an action potential in a neuron?

Threshold of around -55 mV Signup and view all the answers

How does the perceived intensity of stimuli change with increased physical intensity?

Perceived intensity increases slowly Signup and view all the answers

What is the effect of the influx of sodium ions on the neuron's membrane potential during an action potential?

It raises the membrane potential to about +40 mV Signup and view all the answers

What is the primary advantage of low convergence in cones?

Higher acuity for detecting fine details Signup and view all the answers

Which type of photoreceptor is primarily responsible for night vision?

Rods Signup and view all the answers

What happens during dark adaptation?

Rods regenerate photopigments Signup and view all the answers

What is the primary trade-off between rods and cones?

Sensitivity to light versus visual detail (acuity) Signup and view all the answers

During which condition do cones struggle to function effectively?

In dim light conditions Signup and view all the answers

What are the two components that make up visual pigment molecules in the retina?

Opsin and retinal Signup and view all the answers

Which statement correctly describes rods in relation to vision?

Rods increase sensitivity to light in low-light environments. Signup and view all the answers

What best explains the role of convergence in the visual system?

It balances sensitivity to light with clarity of vision. Signup and view all the answers

What is the primary issue faced by individuals with hyperopia?

Difficulty focusing on nearby objects. Signup and view all the answers

Which symptom is associated with retinitis pigmentosa during its early stages?

Night blindness. Signup and view all the answers

What happens to the lens of the eye when focusing on a nearby object?

It becomes thicker to increase light bending. Signup and view all the answers

What is the role of convergence in the eye?

To pool multiple signals from photoreceptors to a single ganglion cell. Signup and view all the answers

What is one disadvantage of high convergence in rods?

Decreased acuity (sharpness of vision). Signup and view all the answers

Which eye part is primarily responsible for providing focusing power?

Cornea. Signup and view all the answers

What condition does macular degeneration primarily affect?

Sharp central vision. Signup and view all the answers

What is the result of the lens flattening when focusing on distant objects?

Reduced light bending. Signup and view all the answers

What is the primary purpose of visual transduction?

To convert light into electrical signals. Signup and view all the answers

Which structure in the retina has the highest sensitivity to light?

Rods Signup and view all the answers

How do cones and rods differ in their convergence onto ganglion cells?

Rods converge more than cones, increasing sensitivity but lowering acuity. Signup and view all the answers

What role do horizontal and amacrine cells play in the retina?

They integrate signals across different photoreceptors and ganglion cells. Signup and view all the answers

What is the effect of dark adaptation on the eyes?

It helps the eye adjust to low light conditions. Signup and view all the answers

Which statement correctly describes the vertical system in the retina?

It directs visual information from photoreceptors to ganglion cells. Signup and view all the answers

What is the primary function of regeneration in the context of visual transduction?

To recombine retinal and opsin for responsiveness. Signup and view all the answers

What is the main contribution of convergence in the retinal structure?

It increases sensitivity to light while reducing visual acuity. Signup and view all the answers

What does double dissociation demonstrate about two cognitive functions?

They rely on different neural pathways and can be independently impaired. Signup and view all the answers

Which of the following best describes Broca's Aphasia?

Speech production is impaired but comprehension remains relatively intact. Signup and view all the answers

What is the role of the ventral pathway in the visual system?

It processes object identity. Signup and view all the answers

What occurs in the brain after visual information is processed by the retina?

Signals travel to the Lateral Geniculate Nucleus (LGN). Signup and view all the answers

What does the presence of double dissociation between Broca's and Wernicke's areas indicate?

The areas are specialized for different aspects of language processing. Signup and view all the answers

Which of the following statements is true regarding single dissociation compared to double dissociation?

Single dissociation may suggest functions are interdependent. Signup and view all the answers

What is the primary function of the dorsal pathway in the visual system?

Processing motion and spatial location. Signup and view all the answers

Which area of the brain is associated with speech comprehension impairment in Wernicke's Aphasia?

Temporal lobe. Signup and view all the answers

Study Notes

Perception and Sensory Processing

Increased physical stimulus intensity leads to smaller increases in perceived intensity (psychophysical principle).
Response expansion occurs when perception increases faster than stimulus intensity, notably in experiences of pain and fear.

Transduction

Transduction describes how photoreceptors (rods and cones) convert light into electrical signals in the retina.
Rods are sensitive to low light and essential for night vision.
Cones are responsible for color vision and visual acuity.

Action Potentials

An action potential is an electrical signal produced by ion movement (Na+, K+) across a neuron's membrane.
Resting potential is when a neuron is at rest, typically around -70 mV, with a negative charge inside.
Sodium (Na⁺) is higher outside the cell, while potassium (K⁺) is concentrated inside; the sodium-potassium pump maintains this balance.

Visual Impairments

Hyperopia (farsightedness) occurs when the eyeball is too short, making nearby objects difficult to focus on.
Retinitis Pigmentosa (RP) is a genetic disorder that causes night blindness and peripheral vision loss, eventually leading to tunnel vision or blindness.
Macular degeneration affects the central retina (macula), causing a loss of central vision while peripheral vision remains intact.

Accommodation

Accommodation is the lens's ability to change shape, becoming thicker for near objects and thinner for distant objects, enabling focus on the retina.

Parts of the Eye

The cornea provides most of the eye's focusing power.
The lens adjusts shape for focused light.
The retina contains rods and cones for light detection.
The optic nerve transmits visual information to the brain.

Convergence in Vision

High convergence is common in rods, enhancing sensitivity to light but reducing acuity.
Low convergence, particularly in cones (especially in the fovea), leads to higher acuity, beneficial for detail recognition but lower sensitivity in dim light.
Trade-off: rods favor sensitivity (ideal for night vision) while cones favor acuity (sharp vision in daylight).

Dark and Light Adaptation

Dark adaptation increases eye sensitivity to low light by regenerating photopigments in rods.
Light adaptation involves reducing sensitivity during bright light exposure.
Visual pigment molecules in photoreceptors include opsin and retinal, critical for converting light into electrical signals.

Organization of Retinal Layers

Five major cell types in the retina: photoreceptors, bipolar cells, ganglion cells, horizontal cells, and amacrine cells.
The vertical system of the retina processes information by moving signals from photoreceptors to ganglion cells.
The horizontal system integrates signals across photoreceptors, enhancing contrast through lateral inhibition.

Double Dissociations

Double dissociations demonstrate that two cognitive functions (e.g., object recognition vs. spatial processing) rely on distinct neural pathways.
Broca’s Aphasia results from damage to Broca’s area, impairing speech production while comprehension remains intact.
Wernicke’s Aphasia occurs due to damage to Wernicke’s area, impairing comprehension while leaving speech production intact, albeit nonsensical.

Visual Pathways

Visual information travels from the retina to the Lateral Geniculate Nucleus (LGN) and then to the Primary Visual Cortex (V1).
The ventral pathway processes object identity (what), while the dorsal pathway processes spatial location and motion (where/how).

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Description

Explore the concepts of perception and stimulus intensity from the perspectives of response expansion and sensory thresholds. Understand how changes in physical intensity relate to perceived intensity and the limitations of human perception. Test your knowledge with this quiz!