Psixologiya fanining predmeti va rivojlanish tarixi

Psycho physical methods 
The branch of psychology which is concerned with the study of relationship 
between physical and psychological phenomenon is called psycho-physics. In this 
sense, the term psycho-physical methods may be referred to all those methods in 
which attempts are made to employ physical devices for the scientific measurement 
of some psychological experiences like sensation of weight, brightness, loudness and 
other such magnitudes. The other complicated psychological phenomena like sleep 
or span of memory etc., can also be studied through the use of such psycho-physical 
methods. 
Three classical psycho-physical methods devised by the German physiologist 
and physicist Gustav Fechner (1801-1887), the father of psycho-physics are still in 
vogue. They are: 
(i) 
The method of minimal changes or methods of limits. 
(ii) 
The method of constant stimuli or the method of right and wrong 
responses. 
(iii) The method of average or mean error. 
These methods are primarily employed to measure absolute threshold and the 
difference threshold. Both the absolute threshold and the difference threshold are 
statistical concepts and both are measured in much the same way. 
 
The absolute threshold may be defined as the minimum value of a physical 
stimulus that reliably produces sensation. Absolute threshold, thus, separates the 
sounds we can hear from those we cannot, the odors we can smell from those we 
cannot, the brightness of the light we can see that which cannot and so on. 
 
The difference threshold may be defined as the minimum difference in value 
between two stimuli that can be perceived by the subject. For example, when one 
experiences a particular weight put on his hand, the difference threshold is the 
minimum weight that should be added to it so that the total becomes distinguishable 
from the first. Let us now give a brief idea of the three psycho-physical methods 
mentioned above.