8C - Visual perception Flashcards
Visual sensation definition
the process of the eye receiving and responding to light from the environment
- captured light information (electromagnetic energy) from the environment by the eye
Visual perception definition
the process of becoming consciously aware of visual stimuli as a result of the interactions between the visual sensory system, and the individual’s internal and external environments
- meaningfully interpreting visual stimuli
Process of visual perception - Selection
- Visual selection process is performed by feature detectors, which are specialised cells along the neural pathway connecting to, and found within, the primary visual cortex
- These cells select and filter out visual signals according to certain perceptually important features
- e.g. some feature detectors respond only to certain colours, shapes, lines and edges
Process of visual perception - Organisation
- Once selected, the visual signals are regrouped and organised to reflect an image of reality
- There are certain guiding principles that help us to group these fragmented signals together again, including our visual perception principles (including Gestalt principles)
Process of visual perception - Interpretation
- Primary visual cortex works with other brain areas to interpret and make sense of the visual stimuli
- Our interpretation of images is influenced by many things, such as past experiences, motives and beliefs, and what is called our perceptual set
Biological factors that influence visual perception:
- Eye
- Optic nerve
- Primary visual cortex
Role of the eye
The organ responsible for receiving light to allow vision
- sense organ for vision
Retina definition
receives and absorbs light, and also processes images
Photoreceptor definition
a cell within the retina that respond to light
The two types of photoreceptors are:
- Rods
- Cones
Specific role or rods
photoreceptors that allow someone to see in low levels of light
Specific role of cones
photoreceptors that allow someone to see colour and fine details in well-lit conditions
Optic nerve definition
the highway of neurons that connects the retina to the primary visual cortex
Primary visual cortex definition
the part of the occipital lobe of the brain that receives information from the eyes
Biological abnormalities
- Colour blindness
- Myopia
Colour blindness definition
a reduced ability to distinguish between certain colours.
There are three main types of colour blindness:
- red-green colour blindness
- blue-yellow colour blindness
- complete colour blindness
Red-green colour blindness
where people struggle to tell the difference between the colours red and green
Blue-yellow colour blindness
where people struggle to tell the difference between the colours blue and green, and yellow and red
Complete colour blindness (also known as monochromacy)
where people struggle to differentiate between colours at all, and often struggle to see clearly
Myopia definition
short-sightedness due to the focal point of one or both eyes being located in front of, instead of on, the retina
Psychological factors that influence visual perception:
- Gestalt principles
- Visual constancies
Gestalt principles definition
The ways in which we organise sensations into perceptions by grouping individual parts of visual stimuli into whole, complete forms, usually in the simplest possible ways
What are 4 Gestalt principles?
- Figure-ground Organisation
- Closure
- Similarity
- Proximity
Figure-ground
allows us to organise a visual scene by differentiating the stimulus (figure) away from the background (ground) on which it appears
Closure
we tend to mentally fill in gaps in a visual stimulus and perceive it as a meaningful whole, a complete form
Similarity
the tendency to mentally group objects with similar qualities together as belonging to a whole.
- features such a size, shape, orientation, texture and colour are all commonly grouped together
Proximity
the tendency to mentally group objects that are positioned closely together
Visual constancies definitions
principles that help maintain the perception of the world as stable, despite changes cast onto the retinal image
Types of visual constancies:
- Size
- Shape
- Brightness (isn’t related to depth)
Size constancy definition
the tendency to perceive the size of objects as being stable, despite changes to the size of the object on the retinal image
Shape constancy definition
the tendency to perceive the shape of the objects as being stable, despite changes to the shape of an object as cast on the retina
Brightness constancy definition
the tendency to perceive an object’s lightness as being stable, despite the amount of light reflected from it
Perceptual set definition
the predisposition to perceive an object in a way that is consistent with our expectations
- the tendency to see in accordance with what were expecting to see
Psychological factors that influence perceptual set
- Past experience
- Context
- Motivation
- Emotional state
- Society and culture
Past experience
the readiness to perceive stimuli in a way that is consistent with what we have previously encountered
Context
we are more likely to perceive a stimulus in a manner that is consistent with the environment in which it appears
Motivation
our motivation affects our perceptual set when our desires create an expectation of what we will perceive
- we are more likely to perceive a stimulus in a way that is consistent with our desire
Emotional state
our emotional tone can also influence our perceptual set
- we have a tendency to interpret/perceive stimuli that is consistent with our emotional state
Social factors that influence visual perception
- Cultural background
- Society
Cultural background
Our cultural background can also influence our perceptual set, predisposing us to perceive visual stimuli in certain ways specific to our cultural context
Holistic perception definition
attention is focused on the broad scene and be aware of relationships and changes
Analytic perception definition
attention is focused on specific objects in the scene and the details of that object, regardless of the context in which the object was presented
