Psychology: Sensory Adaptation and Perception

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Questions and Answers

What is the primary function of sensory adaptation?

To decrease sensitivity to constant stimuli over time (correct)

To enhance the perception of proximal stimuli

To process stimuli in absolute scale

To increase sensitivity to stimuli

What is the effect of high ambient light on the visual system's sensitivity to light?

Sensitivity increases to enhance visibility

Sensitivity remains constant

Sensitivity decreases to prevent overstimulation (correct)

Sensitivity increases to prevent overstimulation

What is the formula for Weber's Law?

ΔI=KI (correct)

ΔI = K/I

ΔI = K*I

ΔI = KI

What is the Weber fraction for loudness?

K ≈ 0.05 Signup and view all the answers

What is the primary difference between visual and auditory adaptation?

Visual adaptation occurs in the visual system, whereas auditory adaptation occurs in the auditory system Signup and view all the answers

What is the effect of low ambient light on the visual system's sensitivity to light?

Sensitivity increases to enhance visibility Signup and view all the answers

What is the term for the smallest detectable change in a stimulus?

Just noticeable difference Signup and view all the answers

What is the Weber fraction for heaviness?

K ≈ 0.02 Signup and view all the answers

What is the primary factor that influences the ability to detect a change in pitch when listening to a constant tone?

Initial pitch Signup and view all the answers

What is an example of somatosensory adaptation?

Wearing a watch initially feels noticeable, but after some time, you stop feeling it Signup and view all the answers

What is the relationship between receptive field size and perceptual acuity?

Receptive field size is inversely proportional to perceptual acuity Signup and view all the answers

What is the characteristic of cone receptive fields in the retina?

Receptive fields vary in size with distance from the fovea Signup and view all the answers

What is the characteristic of retinal ganglion cells?

They respond differently to light in the center versus the periphery of their receptive field Signup and view all the answers

What is the characteristic of hair cells in the cochlea?

They respond to specific frequencies of sound Signup and view all the answers

What is the characteristic of mechanoreceptors in the skin?

They respond to specific types of touch, such as pressure or vibration Signup and view all the answers

What is the relationship between receptive field size and location on the body in the somatosensory system?

Receptive field size is smaller on fingertips and larger on the back Signup and view all the answers

Study Notes

Sensory Adaptation

Sensory adaptation is the process where sensory receptors become less sensitive to constant stimuli over time.
Proximal stimulus is represented on a relative scale, not an absolute scale.
Sensitivity changes depending on the intensity of the background environment.
Contextual influences on perception begin very early in sensory pathways, affecting how stimuli are processed and perceived.

Visual Adaptation

Ambient light sensitivity changes based on the ambient light level.
High ambient light decreases sensitivity to prevent overstimulation.
Low ambient light increases sensitivity to enhance visibility.
Example: Moving from a dark movie theater to a bright sunny day outside makes it hard to see initially due to high ambient light.

Weber's Law

The "just noticeable difference" (JND) is the smallest detectable change in a stimulus.
Formula: ΔI/I = K (where ΔI is the change in stimulus intensity, I is the original stimulus intensity, and K is the Weber fraction).
Weber fractions vary for each type of sensory perception (e.g., loudness, brightness, heaviness).
Example: If you are holding a 100g weight, the smallest detectable weight increase (JND) would be around 2g for heaviness.

Auditory Adaptation & Weber's Law 'Near Miss'

Auditory adaptation is similar to visual adaptation but in the context of sound.
Sensitivity changes depending on ambient noise levels.
Weber's Law 'Near Miss' holds true, but with slight deviations under certain conditions (e.g., very low or very high intensities).
Example: If listening to a constant tone, the ability to detect a change in pitch will depend on the initial pitch and surrounding noise.

Somatosensory Adaptation

Changes in sensitivity of the somatosensory system (touch) over time with constant stimulation.
Example: Wearing a watch initially feels noticeable, but after some time, you stop feeling it due to sensory adaptation.

Receptive Fields

Definition: The specific area of sensory surface to which a neuron responds.
Perceptual resolution and acuity are inversely related to sensory receptive field size.
Smaller fields have higher acuity (e.g., fingertips).
Larger fields have lower acuity (e.g., back).
Example: The receptive field of a cone in the retina is the area on the retina that responds to light.

Visual Receptive Fields

Cone receptive fields are areas on the retina that each cone cell responds to.
Eccentricity: Receptive field size varies with distance from the fovea (center of the retina).
Retinal ganglion cells have receptive fields where action potentials respond to light stimuli.
Center-Surround Receptive Fields: Cells respond differently to light in the center versus the periphery of their receptive fields.
Example: A ganglion cell might be excited by light in the center of its field and inhibited by light in the surrounding area.

Auditory Receptive Fields

Hair cells in the cochlea respond to specific frequencies of sound.
Frequency mapping: Different hair cells are tuned to different frequencies, forming a tonotopic map.
Example: A hair cell might respond best to a 1000 Hz sound frequency.

Somatosensory Receptive Fields

Mechanoreceptors are sensory receptors in the skin that respond to touch.
Field size and acuity vary with location on the body, with smaller fields on fingertips and larger fields on the back.

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Description

Understand the concept of sensory adaptation, proximal stimulus representation, and how context influences perception. Explore how sensory receptors become less sensitive to constant stimuli over time and how contextual factors impact our perception of the world.