Sensation and Perception

• What is the difference between sensation and perception?


  Sensation is the detection of physical stimuli and the transmission of that information to the brain whereas perception is the brains further processing, organisation and interpretation of sensory information.
• What is the difference between bottom up and top down processing?


  Bottom up processing is based on physical features of a stimulus whereas top down processing is based on how knowledge and past experiences shape the interpretation of sensory information.
• What is transduction?


  The translation of stimuli. The process where sensory stimuli are converted to neural signals that the brain can interpret.
• Distinguish between qualitative and quantitative information


  Qualitative information consists of the most basic qualities of a stimulus whereas quantitative information consists of the degree or magnitude of these qualities for example loudness or brightness.
• What is the difference between the absolute and difference threshold?


  The absolute threshold is the minimum intensity of a stimulus necessary to detect a sensation half of the time whereas the difference threshold is the minimum amount of change required to detect a difference between two stimuli.
• Explain Weber's Law


  The more intense the stimulus, the bigger the change needed for you to notice.
• Identify and Describe the 4 Outcomes of Signal Detection Theory

  • Hit: when the signal is presented and the participant detects it.
  • Miss: If the participant fails to detect a present signal.
  • Correct Rejection: If the signal was not there and the participant reports it isn't there.
  • False Alarm: if the participant reports a signal that isn't actually there.
• What is the difference between sensitivity and response bias?


  Sensitivity is determined by what your senses can detect whereas response bias is a tendency that can be biased or pushed around depending on the consequences of the decision.
• What is sensory adaptation?


  A decrease in sensitivity to a constant level of stimulation.
• What is synesthesia?


  When colours evoke smells, sounds and numbers.
• Describe the retina


  The thin inner surface of the back of the eyeball, which contains the sensory receptors that transduce light into neural signals.
• Identify and Describe the two types of receptor cells

  • Rods: respond at low levels of light and result in black and white perception.
  • Cones: respond to higher levels of light and result in colour perception.
• What is the fovea?

  The centre of the retina where cones are packed.
• What is the function of ganglion cells?


  They send signals along the axon from inside the eye to the thalamus.
• Distinguish between the ventral and dorsal stream


  The ventral stream is specialised in perception and recognition of objects such as determining colours and shapes (what stream) and the dorsal stream is specialised for spatial perception such as determining where an object is and relating it to other objects in the scene (where stream).
• Explain the Trichromatic Theory


  Colour vision results from activity in 3 types of cones that are sensitive to different wavelengths. Short wavelengths (blue-violet light), medium wavelengths (yellow-green light) and long wavelengths (red-orange light).
• Explain the opponent process theory


  When we stare at a red image for some time, we see a green after image when we look away. This theory describes the second stage in visual processing.
• Colour is categorised along 3 dimensions. Identify and describe them.


  Hue consists of the characteristics that place a colour in the spectrum for example its redness or greenness. Saturation is the purity of the colour and lightness is the colour's perceived intensity.
• Identify and Describe Gestalts Principles

  • Proximity: the closer a large amount of objects are, increases likelihood of them to be perceived as a group.
  • Similarity: The grouping of objects based on how similar they look in shape, colour etc
  • Good continuation: Grouping edges or contours that are smooth as opposed to those having sharp edges.
  • Closure: Completing figures that have gaps
  • Common fate: seeing objects that move together as belonging to the same group