Visual imagery (VI) is the mental experience of objects in the absence of their corresponding visual stimuli. Asking whether mental images can be physically quantified, we seek for relationships between visual imagery and special relativity. The Einstein’s account states that, by an observer’s standpoint, an object traveling at light speed is subjected to time dilation and length contraction. We hypothesize that objects are contracted both in the physical framework of Einstein’s relativity due to the light speed, and in the mental framework of VI due to the dilated perception of time. Since the duration of thoughts can be experienced as progressively prolonged, we conjecture, in touch with Einstein’s account, that the VI content must consist of objects undergoing length contraction. In the VI dilated mental time, the object might be experienced as more squeezed than the real object. Our calculations based on Einstein’s equations predict that the longer an object is imagined, the more it is experienced as contracted until it disappears from consciousness. In touch with our hypothesis, review of published data provides evidence that distance estimates are shortened during VI. We suggest to evaluate VI in experimental settings where time is perceived as dilated, such as dreams, hypnosis and opioids intake. While the physical account of Einstein’s special relativity is framed on invariant quantities such as the light speed, the mental experience of VI could be framed on non-invariant quantities, namely, quantities that change according to the subjective standpoint of the observer.