  The paper is devoted to the relationship between psychophysics and physics of
mind. The basic trends in psychophysics development are briefly discussed with
special attention focused on Teghtsoonian's hypotheses. These hypotheses pose
the concept of the universality of inner psychophysics and enable to speak
about psychological space as an individual object with its own properties.
Turning to the two-component description of human behavior (I. Lubashevsky,
Physics of the Human Mind, Springer, 2017) the notion of mental space is
formulated and human perception of external stimuli is treated as the emergence
of the corresponding images in the mental space. On one hand, these images are
caused by external stimuli and their magnitude bears the information about the
intensity of the corresponding stimuli. On the other hand, the individual
structure of such images as well as their subsistence after emergence is
determined only by the properties of mental space on its own. Finally, the
mental operations of image comparison and their scaling are defined in a way
allowing for the bounded capacity of human cognition. As demonstrated, the
developed theory of stimulus perception is able to explain the basic
regularities of psychophysics, e.g., (i) the regression and range effects
leading to the overestimation of weak stimuli and the underestimation of strong
stimuli, (ii) scalar variability (Weber's and Ekman' laws), and (\textit{iii})
the sequential (memory) effects. As the final result, a solution to the
Fechner-Stevens dilemma is proposed. This solution posits that Fechner's
logarithmic law is not a consequences of Weber's law but stems from the
interplay of uncertainty in evaluating stimulus intensities and the multi-step
scaling required to overcome the stimulus incommensurability.
