t2: visual perception

• What are the 6 main processes of visual perception?

  Reception, transduction, transmission, selection, organisation and interpretation
• What are the two types of photoreceptors?

  Rods and cones
• What to rods perceive?

  Black and white
• What do cones perceive?

  Colour
• What happens during reception?

  Light enters the eye through the cornea, then passes the pupil, and the lens then focusses on the retina
• What happens during transduction?

  Electromagnetic energy (light) is converted by the rods and cones to electrochemical nerve impulses
• How are photoreceptors organised?

  Into groups called receptive fields
• What happens during transmission?

  Nerve impulses go along the optic nerve to the primary visual cortex in the occipital lobe where specialised receptor cells respond to stimuli and perception begins
• What happens during selection?

  The image is broken up by specialised cells called feature detectors (found in optic nerve and primary visual cortex) that respond to lines of a certain length, angle or moving direction
• What happens during organisation?

  Information travels to the temporal lobe to identify objects and parietal lobe to judge where objects are in space
• What happens during interpretation?

  The stimulus is given meaning, which occurs in the temporal and parietal lobes
• What are the three biological influences on visual perception?

  Physiological makeup, ageing and genetics
• What does physiological makeup refer to?

  Impairments or damage to structural parts of the visual system that creates problems with function
• What is colour blindness?

  Damage or deterioration of cones (retina) and therefore problems processing colour
• What are the three types of colour blindness?

  Monochromacy, dichromacy and trichromacy
• What happens in monochromacy?

  Brightness is detected and black and white only
• What happens in dichromacy?

  Tow or more cones deteriorate and there is therefore a reduced colour palette detected
• What happens in trichromacy?

  There is an impaired sense of colour
• What are two examples of diseases caused by physiological makeup?

  Colour blindness and achromatopsia
• What are the causes of achromatopsia?

  It can be congenital (cones) or caused by damage to the brain (neural pathways)
• What happens in achromatopsia?

  Can see black and white only and there is damage to cones
• What are the five examples of diseases caused by ageing?

  Presbyopia, floaters, cataracts, age-related macular degeneration and glaucoma
• What happens in presbyopia?

  The lens loses elasticity so there is difficulty focussing on close objects
• What happens when you have floaters?

  Clumps of matter float in the vitreous humour, which cause spots in vision
• What happens when you have cataracts?

  The lens is cloudy due to protein breakdown, which causes blurry vision
• What happens in age-related macular degeneration?

  There are grainy deposits in the macula, which causes blurring
• What happens when you have a glaucoma?

  There is optic nerve damage so no peripheral vision and leads to blindness
• What are the four parts of the perceptual set?

  Past experiences, context, motivation and emotion
• What are the five Gestalt principles?

  Figure-ground, camouflage, closure, similarity and proximity
• What are the two classifications of depth perception?

  Binocular and monocular
• What are the two classifications of depth perception?

  Binocular and monocular
• What are the two binocular principles?

  Retinal disparity and convergence
• What are the two monocular principles?

  Accommodation and pictorial depth cues
• What are the five pictorial depth cues?

  Linear perspective, interposition, texture gradient, relative size and height in the visual field
• What are the three fallibilities of visual perception?

  The Ponzo illusion, the Muller-Lyer Illusion and the Ames Room Illusion
• What is the Ponzo illusion?

  Where the perception of lines is consistently different from objective reality
• What pictorial depth cues are misapplied in the Ponzo illusion?

  Linear perspective and height in the visual field
• What are the two hypotheses regarding the Müller-Lyer Illusion?

  Perceptual Compromise Theory and the Carpentered world hypothesis
• What is the perceptual compromise theory? (Müller-Lyer Illusion)

  It is the psychological explanation and states that this occurs due to the misapplication of closure
• What is the carpentered world hypothesis? (Müller-Lyer Illusion)

  It is the social explanation and states that shape constancy is maintained over size constancy