| Object recognition in humans | can identify objects and understand how to interact with them
e.g. mountain |
| what are Feature detectors: | feature detector neurons in the visual cortex responded to features such as lines, dots, colours etc |
| Brain part for feature detectors | Dorsal visual stream - determines 'where is it?' - spatial awareness of an object |
| what is Pattern Recognition? | we often perceive the whole before the final details
psychologist found performance speed with small letters was slowed if the larger letter was different |
| What are the laws of Gestalt psychology? | 1. Law of proximity
2. Law of similarity
3. Law of good continuation
4. Law of closure |
| Definition of Law of proximity | visual elements close in space are grouped together |
| Definition of law of similarity | similar elements are grouped together |
| definition of law of good continuation | elements grouped together requiring fewest changes or interruptions in straight or smoothly curving lines |
| definition of law of closure | missing parts of a figure are filled to complete the figure |
| What is bottom-Up processing? | purely what you observe and see |
| what is top-down processing? | using prior knowledge to identify what an object is |
| what is the law of Pragnanz? | we perceive the simplest possible organisation of the visual field |
| weakness of gestalt psychology | contrary evidence found
compared background identification of familiar and unfamiliar objects
amnesic patients showed no differences in identifying background of familiar and unfamiliar stimuli |
| What is the spatial frequency theory? | suggests 2 systems
1. quickly process low spatial frequency
2. process high spatial frequency milliseconds later |
| spatial frequency and ventral/dorsal stream: | low spatial frequency: processed by fast magnocellular pathway
high definition details - processed by parvocellular pathway |
| what is low spatial frequency? | this is fast processing and seeing the whole object |
| what is high spatial frequency? | processing looking at the details |
| spatial frequency theory | different neurons in visual cortex respond to high vs low spatial frequencies
focus on the whole and then details if we want to |
| object recognition theory | 1. stimulus --> a primal sketch of stimulus --> 2.5D sketch --> 3D model --> object |
| recognition by components theory | all objects are made up of basic shapes (geons) - e.g. cylinders, blocks, arcs etc |
| top down Bar et al theory | top-down processes in orbitofrontal cortex are more important when recognition of objects is difficult |
| interactive-iterative framework | top-down processes (context) influence allocation of attention
attention influences bottom-up processing
knowledge drives searching for features
this repeats until object is recognised
(only for difficult objects) |
| facial recognition | repeated exposure to the face leads to better recognition |
| how do humans recognise faces? | Holistically (look at whole face not details)
more rapid than object recognition
more reliable than object recognition |
| face inversion effect | humans are slower at identifying faces when they are inverted |
| Face blindness 'prosopagnosia' | individuals with this issue cannot recognise faces
this is severely impaired face processing |
| prosopagnosia evidence | researcher showed familiar and unfamiliar faces to a proropagnostic (PS) who didn't recognise any of the faces familiar or not
however, PS showed more activation in brain area associated with face recognition when seeing familiar faces
1. damage to brain area specific to face processing
2. facial recognition of a specific person more difficult that identifying category (i.e. bird, car etc) |
| Double dissociation in prosopagnosia patients | some PP patients have poor facial recognition but o object recognition
there could be a double dissociation if there were ppts who had good facial recognition but bad object recognition
case studies of individuals who have this are available - more research is still needed |
| What is the 'fusiform face area'? | a section of the brain associated with face processing
patients with pp have damage to occipital face area as well as fusiform area |
