Capacity limitations in the perception of letters Endel P

1
Capacity limitations in the perception of
lettersEndel PõderTallinn Pedagogical
University, 25 Narva Road, Tallinn 10120,
EstoniaE-mail ep_at_tpu.ee
Introduction Comparing observers performance
under the conditions of successive and
simultaneous presentation of visual stimuli can
reveal capacity limitations of information
processing. Earlier studies have found no or
relatively small differences between successive
and simultaneous presentation of alphanumeric
characters (Duncan, 1980 Kleiss Lane, 1986
Shiffrin Gardner, 1972). Usually, small sets
of letters (e g 2 and 4) have been used.

• Results
• No difference between for successive and
  simultaneous conditions for set-size 4.
• A large advantage of successive presentation for
  set-sizes 8 and 12 letters.

Three observers
Purpose of the present study To compare the
successive and simultaneous presentations with
larger sets of presented letters
Methods Visual search experiment Observers had
to detect a target letter among 4, 8, or 12
random letters. The letters were presented
briefly (20-100 ms) either simultaneously, or in
two successive groups with interval of about
1s. Target was present with probability 0.5 (for
successive condition, either in first or second
display, with equal chances).
Conclusion There seems to be a limit of
processing capacity at about 4 letters per brief
presentation.
Simultaneous
References Duncan, J. (1980) The locus of
interference in the perception of simultaneous
stimuli. Psychological Review, 87,
272-300. Kleiss, J. Lane, D. M. (1986) The
locus and persistence of capacity limitations in
visual information processing. Journal of
Experimental Psychology Human Perception and
Performance, 12, 200-210. Shiffrin, R. M.
Gardner, G. T. (1972) Visual processing capacity
and attentional control. Journal of Experimental
Psychology, 93, 72-82.
Successive
T1
T2