1. Capacity limitations in the perception of letters Endel Põder Tallinn Pedagogical University, 25 Narva Road, Tallinn 10120, Estonia
Introduction
Comparing observer’s 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 ( 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,
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,
Shiffrin, R. M. & Gardner, G. T. (1972) Visual processing capacity and attentional control. Journal of Experimental Psychology, 93,
Successive T1 T2