Page:Mind (New Series) Volume 9.djvu/401

PERCKI'l [OX OF CHANGK AM) DURATION. r!<S7 the shock occasioned by B. If it suffices to compare the memory- iniiige of this symbol of A with the percept B during the actual perception of B, then 1 should say that no very strict differentiation of the actual sound-intensity B and the subjective shock takes place ; but the comparison is rather with the shock than with B itself. However, such conditions seeiu to be rarely realised in cases of difficult comparison ; rather, we take time to consider the matter before answering. The result is that B itself, if caused by a momentary stimulus, passes away, and then I have no doubt that the memory-image of the symbol of A is compared with the memory-image of the symbol of B. Indeed, I notice a tendency in very hard cases to imitate the shocks by other means, e.g., by movements of the lower jaw, head, or hand, but never any attempt to imitate the sound-intensities by rapping on the table or the like. This is probably due to a very defective auditory memory, but much the same occurs elsewhere. As a rather different example I may cite the case of voluntary movements. In experi- ments on such movements of the arm carried out on Storring's apparatus, 1 the simplest manner for the blindfolded subject to decide whether one flexion or extension was equal or not to another would seem to be a direct comparison of the series of so-called ' movement-sensations '. As a matter of fact, these were never except in very large movements the conscious factors that determined my judgment, nor indeed could I by any amount of effort distinguish these sensations as a rule ; but I made use of various complex ideas of direction, distance, position, etc., and the ideas that were most prominent in movements on one part of the apparatus were often least prominent in other parts. This seems to be a case where, to judge from what is actually present in con- sciousness, a roundabout way is preferred to a short cut. Thus, whilst subscribing to Dr. Stout's theory as a whole, I should like to venture a generalisation from my own case and give the state- ment a more precise form, as follows : The apprehension of a presentation B as different from a previous presentation A does not necessarily imply the coexistence in consciousness with B of a perceptual or memorial image of A. If B follows A with sufficient rapidity, they fall within one perception and so are present together. Otherwise A is usually not present if the difference is easily ap- prehended. But when the comparison can only be effected with difficulty i.e., when there is true comparison it usually happens either that a memory-image of A itself is compared with the percept B or with a memory-image of B, or that a memory-image of some experience that is recognised as standing as a symbol or formula for A is compared with a similar formula for B or with the memory-image of such a formula. 1 The apparatus is described in Phil. Stud., xii., 475. The experi- ments mentioned were under Dr. Storring's leadership, and as his account of them has not yet appeared, an apology is due for this previous, though very cursory, mention of them.