VISUAL PERCEPTION, CORTICAL PROCESSING AND MOTOR EFFECTS
Main researcher
: KOLESARIĆ, VLADIMIR (21736) Assistants
IVANEC, DRAGUTIN (180316)
Type of research: basic Duration from: 04/01/91. to 04/01/94. Papers on project (total): 11
Institution name: Filozofski fakultet - Humanističke znanosti, Zagreb (130) Department/Institute: Department of Psychology Address: Salajeva 3, City: 10000 - Zagreb, Croatia
Communication
Phone: 385 (0)1 6120-196
Fax: 385 (0)1 6120-037
E-mail: vkolesar@ffzg.hr
Summary: Five laboratory investigations have been carried out. (1)
In the experiment with simple reaction time as the dependent variable,
its stability in time and dependance on stimuli context was elucidated.
Reaction time may be affected by many factors which are irrelevant to the
relationship of the independent and dependent variable, but subjects tend
to have a similar reaction dynamics over longer time periods. Results
suggest that the impact of stimuli context is to some extent cognitively
mediated. The results of our recently conducted experiments, shich shows
that subjects' reaction expectation are related to stimuli context support
that conclusion.(2) The results obtained by the divided visual field
technique are in keeping with the model presuming that the cerebral
hemispheres are two processors, each comprising a number of subsystems and
modules. Given that both hemispheres are able to process verbal stimuli,
when interpreting the differences the characteristics of verbal and the
mode of their presentation should be taken into account. (3) By
effectuating total restriction of information on distance of the viewed
object it was still possible to estimate its size: the size of the
afterimage projected on the perceptually accessible distance was in
accordance with the visual angle law. (4) The obtained direction of the
difference in the perception of brightness of indirectly illuminated
surfaces depends on the sharpness of illumination edges. This result is in
keeping with the hypothesis that the color of an object is decoded on the
basis of the sharpness of edges which, in turn, depends on the magnitude
of indirect light. (5) Exponents of psychophysical functions obtained by
the magnitude estimation method with or without a presented standard did
not differ significantly. Various calculation techniques of the exponent
in the situation without the standard yielded equal values.
Research goals: The general objective of the project was to explore,
by carefully designed and performed laboratory experiments, several basic
issues on the functioning of the human as a reactive system. To this end
experiments were carried out in the field of visual and auditory perception
(input), cerebral hemispheric function (central processing), and motor
reaction in its simple form, i.e. simple sensorimotor reaction (output).
Given that these are basic issues of scientific psychology, the obtained
results are only one of the contributions to the issues raised, although
the mentioned stages of functioning have many dimensions and may be
explored in a variety of ways. Considering the results of the particular
experiments the conclusion may be reached that the objective has been met:
data on reaction time stability and stimuli context impact have been
obtained; it has been found that it is not warrantable to interpret all
differences between left and right visual fields as a result of hemispheric
specialization; that it is possible to objectively assess the apparent size
of the object image; that the perception of indirect illumination depends
on the sharpness of edges of perceived surfaces; that various procedures of
the determination of the psychophysical function exponents do not yield
significantly different values. Other information about the project.