gestalt psychology
Concerned with how perceptual organisation is achieved
Describe how we separate + link into individual objects
guiding principles of gestalt psychology
- similarity
- proximity
- good continuation
- closure
- simplicity
similarity
group together objects that resemble each other
proximity
The closer objects are to each other, the more likely to group them together perceptually
good continuation
Prefer to organise objects where contours continue smoothly
closure
Bias towards perceiving closed objects rather than incomplete ones
simplicity
Interpret an object in the simplest way possible
figure ground segregation
separating an object from its background
strengths of figure ground segregation
Focuses on fundamental issues
Principles applicable to complex images
Simplicity is key
weaknesses of figure ground segregation
Deemphasised the importance of past experience
Provide descriptions of perceptual phenomena
Principles of perceptual organisation based on 2D drawings
is figure ground segregation innate?
Indicate which region (black or white) is a figure (Barense et al. 2011)
Healthy controls: identified regions containing familiar configuration as figure more often than novel configuration
Amnesia: no difference in figure ground decisions for familiar or novel configurations
- Figure ground perception relies on past experience / learning
feature detection theories
A simple pattern, fragment or component
- Appears in combo with other features across a variety of stimuli
visual search
Indicate as quickly as you can whether a particular target is present
Takes longer when searching for a combo of features
geometric ions
Recognition by components (RBC) theory
All objects reduced to geometric ions (geons)
RBC theory
Perceiving objects is the first major step in object recognition
Object recognition is a joint effort between two processes:
1. One responsible for features + components
2. One responsible for overall shape + global patterns
evidence for RBC
If a pattern is degraded, it matters where its degraded
Non recoverable objects
Vertices (points where two lines meet) missing
Cannot / take longer to recognise objects
Recoverable objects
Segments of smooth, continuous edges missing
Easy to fill in missing parts + recognise object
weaknesses of RBC
Tied to bottom up processing
Some evidence contradicts the ‘features-first’ aspect of the model
Whole object can be perceived rapidly + automatically
Embodied cognition
Perception of objects influenced by our expectation of how we will interact with those objects
what is perceptual constancy?
We perceive the constant properties of objects in the world; despite sensory info changing
Essential aspect of perceiving objects
Needed to perceive what something is
examples of perceptual constancy
- Size constancy
Correctly perceive size on objects, despite changes in size created by viewing distance - Shape constancy
Correctly perceive shapes of objects despite changes in viewing angle - Colour constancy
Correctly perceive same colour of an object despite changes in the wavelengths
object comparison
How do we achieve perceptual constancy?
Compare target object with those in the background
Role of interpretation
The “monster illusion”
Misperception of size
binocular cues
Each eye has a different view of the world (stereopsis)
Difference = binocular disparity
oculomotor cues
Convergence: eyes turn inwards when we focus on close objects
Accommodation: shape of lenses in eye changes shape depending on an object’s distance
monocular (pictorial) cues
Interposition / occlusion: blocking of our view of one object by another
Linear perspective: parallel lines seem to converge as they get farther from the viewer
Texture gradients: as surface gets farther away, its texture appears finer + smoother
motion cues
Motion parallax: nearby objects move more rapidly than far away objects
Optic flow: images get larger as we approach them
