Sensation and Perception

Define sensation

Sensation is the process by which sense organs gather information about the environment and transmit it to the brain for initial processing.

Define Perception

Perception is the process by which the brain selects, organises and interprets sensations.

Explain the three basic principles that apply across all areas

Three basic principles apply across all senses.

1. There is no one-to-one correspondence between physical and psychological reality.

2. Sensation and perception are active, not passive.

3. Sensory and perceptual processes reflect the impact of adaptive pressures over the course of evolution.

How does sound travel

Sound travels in waves, created when a vibrating object sets air particles in motion.

What determines the pitch and loudness of a sound?

Pitch is determined by the frequency (oscillations per second), and loudness is determined by the amplitude (height and depth) of the sound wave.

How does sound reach the eardrum?

Sound waves travel through the auditory canal to the eardrum.

What happens after the eardrum receives sound?

The eardrum sets the ossicles (tiny bones) in motion, amplifying the sound.

Where does transduction of sound occur?

In the ear — where physical sound energy is converted into neural signals.

What are the roles of the outer, middle, and inner ear?

• Outer ear: collects and magnifies sound.

• Middle ear: converts air pressure waves into movement of bones.

• Inner ear: converts bone movement into fluid waves, then into neural signals

What are the two basic processes in the eye?

• Light is focused on the retina by the cornea, pupil, and lens.

• The retina converts the image into a neural code the brain can interpret.

How does visual information travel from the eye to the brain?

Via the optic nerve, it travels to the:

• Superior colliculus (involved in eye movements)

• Lateral geniculate nucleus (in the thalamus)
  Then on to the primary visual cortex.

What are the two visual pathways beyond the primary visual cortex?

• The "what" pathway (identifying objects)

• The "where" pathway (locating objects in space)

What does the Young–Helmholtz (trichromatic) theory state?

The eye has three types of receptors sensitive to red, green, or blue wavelengths.

What does the opponent-process theory state?

Colour vision is based on three opposing systems:

• Blue–Yellow

• Red–Green

• Black–White
  These explain colour perception and after-images.

Where does transduction of smell (olfaction) occur?

In the olfactory epithelium — a thin pair of structures at the top of the nasal cavities.

Where does transduction of taste occur?

In the tastebuds, which are distributed throughout the mouth and throat.

What do the proprioceptive senses detect?

They register body position and movement. These include:

• Vestibular sense (balance and spatial orientation)

• Kinaesthesia (awareness of body movement)

What is transduction?

Transduction is the process of converting stimulus information into neural impulses.

What is the absolute threshold?

The minimum amount of energy needed for an observer to detect that a stimulus is present.

What is the difference threshold?

The smallest level of stimulation required to detect that a change has occurred in the stimulus.

What is sensory adaptation?

The tendency of sensory systems to respond less to stimuli that continue without change.

What is subliminal perception?

The tendency to perceive information that occurs outside of conscious awareness.

What is perceptual organisation?

It integrates sensations into percepts, locates them in space, and maintains their meaning from different viewpoints.

What are the four aspects of perceptual organisation?

• Form perception

• Depth or distance perception

• Motion perception

• Perceptual constancy

What is perceptual interpretation?

The process of generating meaning from sensory experience.

How does memory influence perception?

Perceptual interpretation happens at the intersection of sensation and memory — the brain uses past experience to interpret current sensations.

What is bottom-up processing?

Perception thay is shaped by sensory input, starting with raw data. there is no preconveived idea of what the stimulus is, the stimulus influences ur perception of what you are looking at.

What is top-down processing?

Perception guided by prior knowledge, expectations, and experience.

What is signal detection theory?

It proposes that sensation involves making a judgment about the presence or absence of a stimulus, rather than passively responding once a threshold is passed.

What is Weber’s Law?

Weber’s Law states that the just noticeable difference (jnd) between two stimuli is a constant proportion of the original stimulus, not a fixed amount.

What is Fechner’s Law?

Fechner’s Law states that the subjective intensity of a sensation increases logarithmically as the actual stimulus intensity increases.

What is Stevens’ Power Law?

It’s a refinement of Fechner’s Law that describes the relationship between stimulus intensity and perceived magnitude using a power function rather than a logarithmic one.