Introduction to Sensation and Perception

Introduction to Sensation and Perception

• Sensation is the process of receiving information from the environment.
• A stimulus is a detectable input from the environment.
• Types of stimuli include light (vision), sound (hearing), chemicals (taste and smell), pressure, temperature, pain (touch), orientation, and balance (kinesthetic).

Transduction and Perception

• Transduction is converting stimulus energy into neural activity, recoding the stimulus as a neural pattern.
• Perception is selecting and identifying information from the environment.
• Perception is the interpretation of this information to understand its meaning.

Thresholds

• Absolute threshold: The weakest stimulus that can be detected 50% of the time.

• Examples of absolute thresholds:

  • Sight: seeing a candle flame 30 miles away on a clear night
  • Hearing: hearing a watch ticking 20 feet away
  • Touch: feeling a bee's wing falling a distance of 1cm onto your cheek
  • Smell: smelling one drop of perfume in a three-room house
  • Taste: tasting one teaspoon of sugar dissolved in two gallons of water

• Difference threshold (JND): The minimal change in stimulation that can be reliably detected 50% of the time.

• Weber's Law: The just noticeable difference is a constant percentage rather than an absolute amount.

Signal Detection Theory

• Signal detection theory suggests how individuals detect a minimal stimulus (signal) among other background stimuli (noise).
• This can be influenced by factors like sensitivity and criterion.
• Key terms:
  • Hit: Correctly recognizing a stimulus is present
  • Miss: Thinking a stimulus is not there when it is
  • False alarm: Thinking a stimulus is present when it isn't
  • Correct rejection: Correctly recognizing that a stimulus isn't present

Sensory Adaptation and Habituation

• Sensory adaptation is a decline in receptor activity when stimuli are unchanging.
• Habituation or adaptation is a decline in response to a stimulus due to repeated presentation; this happens at the neural level.

Sensitivity and Criterion

• Sensitivity: How easily a stimulus can be detected accurately.
• Criterion: How sure we want to be before deciding that a stimulus is present.

Vision

• Vision begins with light entering the eye.
• Human photoreceptors are sensitive to wavelengths of light energy (the visible spectrum, from red to violet).
• The retina contains photoreceptors (rods and cones) that transduce light energy into electrochemical energy.

Photoreceptors

• Cones provide daytime vision and color perception.
• Rods provide vision in dim light.

Color and Color Vision

• Hue: What is typically meant by color. Hue comes from wavelengths of light being reflected more than others. White, black and gray lack hue because they reflect all wavelengths approximately equally.
• Saturation: The hue relative to the amount of white. Adding white reduces saturation.
• Brightness: The intensity of the light; objects that reflect more light appear brighter.

Theories of Color Vision

• Trichromatic theory: Suggests three types of color receptors (sensitive to different parts of the spectrum) that allow us to see color.

• Color deficiencies common in males because of inheritance pattern on the X chromosome.

• Opponent-process theory: Suggests color receptors are sensitive to opposing pairs of colours (e.g., red/green, blue/yellow, black/white), which are stimulated by one and inhibited by the other.

• Ishihara color test: Used to identify color deficiencies.

Audition

• Begins with sound entering the ear, which is a form of mechanical energy caused by vibrating objects.
• Sound waves carry this energy. Sensitivity to and interpretation of these waves depend on different factors.

Characteristics of Sound

• Frequency: Number of waves per second, measured in Hertz. It is perceived as pitch, higher frequency means a higher pitch.
• Amplitude: Height of wave, measured in decibels. It is perceived as loudness.
• Exposure to loud sounds can damage hearing.

Gustation (Taste)

• Taste buds contain receptors sensitive to taste.
• Types of taste: sweet, sour, salty, bitter, umami
• Factors like cross-adaptation influence taste perception.
• There are different levels of sensitivity to taste (non-tasters, tasters, super-tasters).

Olfaction (Smell)

• Olfactory epithelium area in the nasal cavity where olfactory sensory neurons (involved in processing smell) are located.
• Odors can evoke strong emotional memories.
• On average women tend to detect and experience odors stronger than men.

The Vestibular Sense

• Provides a sense of balance and awareness of body position.
• Issues include dizziness, ringing/roaring in ears, pressure/pain in affected ears and hearing loss.

Somatosensation (Touch)

• Includes sensations like cold, warmth, pressure, and pain.
• Receptors in the skin are responsible for detecting these sensations.

Pain

• Nociceptors are nerve endings sensitive to pain.

• Some pain receptors respond to pressure (e.g., hitting your thumb), others to extreme heat or cold.

Haptic Perception

• Touch perception and kinesthesis are involved, for example, in Braille reading or finding keys in the dark.

This quiz explores the fundamental concepts of sensation and perception, including the processes involved in detecting and interpreting stimuli from the environment. It covers transduction, types of stimuli, and thresholds essential for understanding sensory experiences.