Psych ch-3 3/3/2013 10:28:00 PM
Form perception – process through which you manage to see basic shape and size of object
Object recognition – process through which you identify that the object is
OR is essential whenever you want to apply your existing knowledge to world and
new learning – useful to combine the newly learned information to one already
Gestalt psych – perception of visual world is organized in way that stimulus is not – hence
organization is done and must be provided by perceiver
Perception of perceiver goes beyond information given in drawing (ex. Necker cube)
by specifying arrangement in depth
Reversible objects requires reinterpretation – because there are two prominent and
stable interpretation of figure. Both of figures tend to flip from organization to other
Figure/ground organization – the determination of what is figure (depicted object
displayed against a background) and what is ground.
- information reaching eyes is constant, geometry of figure remains exact same.
Change occurs only in perceiver, by organizing and interpreting is differently.
Perception goes beyond information given.
Proximity and similarity – assume contours are smooth, not jagged; avoid
interpretations that involves coincidences:
o Similarity – tend to group dots into columns rather than rows, according to
similar color of dots
o Proximity – tend to perceive groups, linking dots that are closer to each other
o Good continuation – tend to see continuous bar at background rather than two
similar triangles divided by foreground
o Closure – tend to perceive intact triangle, reflecting our bias towards closed
figures rather than incomplete ones.
o Simplicity – tend to interpret a form in simplest way – interpret as 2
intersecting figures rather than 12-D figure
Organization and features – two broad steps: first collect info about stimulus (what corner,
angles, color it has) and then interpret info (go beyond what’s given)
Interpretation happens before we collect raw data – one time the figure is presented
plainly but provided with info, it becomes meaningful – features themselves depend
on how form is organized by viewer, are much in the eye of beholder. Analysis of
features depend on step in which figure is first organized by viewer
Features must be in place before interpretation is offered because features govern the
interpretation Brain areas that analyze pattern’s of basic features do work at same time as brain
analyzing large scale configuration – these areas interact, hence perception of features
is guided by configuration and configuration is guided by features.
Object recognition –
- we tend to recognize objects even when information given is partial – only a face and tail of
cat, recognize chair even someone sitting on it is covering it completely
- recognition of objects is influenced in important ways by context in which objects are
some influences come directly from stimulus itself, called stimulus driven – bottom-
up – (effects governed by stimulus input; shape the processing of that input)
some influences come directly from perceiver, in which you go beyond info given,
relying on knowledge perceived earlier, called knowledge or expectation driven,
called top-down influence – (factors arising from your knowledge and expectations
and thus shaping your processing of stimulus input)
Features:- We tend to recognize elephant by its trunk, big legs but it is possible that we may
tend to perceive him as elephant by looking at parts of their parts. ex. Circle in trunk, parallel
lines in leg
Visual features – recognition may start with identification of visual features – vertical
lines, curves, diagonals, etc.
Focusing on features may allow to concentrate on what’s common and recognize
remarkably fast and efficient when searching for target defined by simple feature -
one vertical line in 10 horizontals, one green in 10 reds, etc.
Much slower in searching for target defined as combination of feature – one green
vertical in mix green-red shapes.
Damage to parietal cortex – disorder integrative agnosia – normal in tasks that
requires them to simply detect particular features in display but impaired to judge
how features are bound together to form complex objects
TMS showed no difference during disruption in parietal lobe defined by single feature
net but showed dramatic slowed performance when asked to find target by combo of
Word recognition:- object recognition begins with detecting simple feature nets but once
recognition has taken place, next step is to put them together to make objects complete
Factors influencing recognition – familiarity and recency Tachistoscope – is a device designed to present stimuli for precise controlled time.
Each stimulus is followed by mask – random jumbled letter, serves to interrupt any
o Familiarity – words are are frequent or more familiar to participants, were
able to recognize twice as many of frequent words even after masking than
non familiar ones
o Recency - if person has viewed word already, second time they will recognize
it much more faster. First exposure primes participant for second, or
repetition priming –
Word superiority effect – words easy to read than isolated letter
o Higher accuracy in identifying letter that appears as a word rather than
appearing as letter by themselves
Degree of well-formedness – pronounceability and englishness
o Easily pronounceable words provide context benefit, easy to recognize after
o Enlishness – letter strings which resemble spelling patterns of English
language are more easily detectable, good predictor of word recognition,
greater context benefit
o Context promote letter recognition only if context has normal spellings. If not
normal spelling, then does not promote letter recognition
o Stronger tendency to misread less common and irregular pattern letter
sequences ex. Misread as Trum but Drum cannot be misread.
o Misspelled words, partial words or non-words are still read in way that brings
them into line with norma