biological factors visual perception

• Visual Sensory System

  The network that is involved in the sensation and perception of visual stimuli, including the eyes, the brain, and the neural pathways connecting them
• Visual Stimuli

  External stimuli of light
• Visual Sensation

  The stages of processing incoming visual stimuli. The sensory stimulus is received by the sensory receptors, light travels through the eye and is projected onto the retina, and light energy is converted into a neural message and sent to the brain
• Visual Perception

  The process of becoming consciously aware of the stimuli as a result of the interactions between the visual sensory system, and the individual's internal and external environments
• Feature Detectors

  Specialised cells along the neural pathway connecting to, and found within, the primary visual cortex
• Stages of Visual Perception

  1. Selection

  2. Organisation

  3. Interpretation
• Selection

  Only some visual stimuli is selected for attention. Visual selection process is performed by the feature directors. These cells select and filter out visual signals according to certain perceptually important features
• Organisation

  Visual signals then are regrouped and organised to reflect an image of reality
• Interpretation

  The primary visual cortex work with other brain areas to interpret and make sense of the visual stimuli
• Biopsychosocial model

  A model that considers biological, psychological and social factors
• Biological Factors

  Internal, genetic and/or physiologically based factors
• Photoreceptors

  The sensory receptors of the eye which receive light and convert this sensory information into a form that can be sent to the brain
• Rods

  Photoreceptors that allow someone to see in low levels of light
• Cones

  Photoreceptors that allow someone to see colour and fine details in well-lit conditions
• Rods


  • Respond well to low levels of light
  • Specialised for night vision
  • Do not process colour vision
  • Do not process fine detail
  • Located mostly on the outer edges of the retina
  • Allow peripheral vision
• Cones


  • Respond well to bright light conditions
  • Specialised for day vision
  • Process colour vision
  • Process fine detail
  • Most densely concentrated in the center of the retina
  • Do not allow peripheral vision
• Colour Blindness [Achromatopsia]

  Caused by the cones of the eye. Three main types: red-green colour blindness, blue-yellow colour blindness, complete colour blindness
• Refractory Errors

  Abnormalities in the shape of the cornea and lens in the eyes can cause the eye not to bend light as it is supposed to – resulting in reduced visual acuity
• Short Sightedness [Myopia]

  Focal point of one or both eyes being located in front of, instead of on, the retina. Close objects = fine, far away objects = blurry/indistinct
• Depth Cues

  Visual cues that allow someone to perceive the world in three dimensions and judge the distance and position of objects in their environment
• Monocular Depth Cues

  Rely on visual information perceived by just one eye
• Binocular Depth Cues

  Rely on visual information from both eyes
• Accommodation

  Involves our lens bulging and flattening according to how far away an object is. This is how our eyes accommodate for distance
• Motion Parallax

  Uses our perception of movement to help us gauge how far away things are. Helps us to measure depth – the less objects in our visual field move, the further they are away from us
• Monocular Pictorial Depth Cues

  • Relative Size
  • Height in Visual Field
  • Linear Perspective
  • Interposition
  • Texture Gradient
• Relative Size

  The relative size of the objects to one another in our visual field helps us to judge distance
• Height in Visual Field

  The closer objects are to the horizon, the further away they appear
• Interposition

  When objects overlap with one another, we perceive the object that is covered by another as being further away than the one that is obscuring it
• Texture Gradient

  We rely on the use of texture to judge how far away objects are. The closer we are, the greater the detail of texture we can see. The further away we are, the less detail we can see
• Linear Perspective

  Parallel lines within our visual field appear to gradually converges (come together) as they recede into the distance. This allows us to gauge distance
• Retinal Disparity

  The difference/disparity between the different images received on the retina on either eye. The closer an object is to our eyes, the greater the disparity
• Convergence

  The turning inwards of our eyes, and the resulting strain it produces, when an object is close. The strain caused by our eyes turning inwards sends signals to our brain that something is close
• Visual Sensory System:

  the network that is involved in the sensation and perception of visual stimuli, including the eyes, the brain, and the neural pathways connecting them
• Visual Perception:

  the process of becoming consciously aware of the stimuli as a result of the interactions between the visual sensory system, and the individual’s internal and external environments.
• Feature Detectors:

  specialised cells along the neural pathway connecting to, and found within, the primary visual cortex
• Stages of visual perception - selection

  Only some visual stimuli is selected for attention. Visual selection process is performed by the feature directors. These cells select and filter out visual signals according to certain perceptually important features.
• stages of visual perception - organisation

  Visual signals then are regrouped and organised to reflect an image of reality.
• stages of visual perception - interpretation

  The primary visual cortex work with other brain areas to interpret and make sense of the visual stimuli.
• Photoreceptors:

  the sensory receptors of the eye which receive light and convert this sensory information into a form that can be sent to the brain.
• Rods:

  photoreceptors that allow someone to see in low levels of light.