Perceived movement of the afterimage during eye movements

Abstract

"When the eyes move, the after-image moves in the same way [Helmholtz, 1924]." Since Helmholtz, if not before, it has generally been assumed that an afterimage would appear to move if the eyes were moving while it was viewed. The general basis of this notion is the phenomenon of position constancy: the fact that despite movements of the 0 that cause the image to move over the retina, a stationary scene will continue to look stationary. It is plausible to believe that position constancy is the result of a process in which image displacement that is concurrent with movement does not lead to the perceived movement of the objects whose images are displacing, because under these conditions the displacement is taken into account and movement is attributed to the 0 himself. Thus, image displacements dependent on 0 movement are taken into account so that the objects in the visual field appear stationary and the 0 experiences himself or some part of himself to be moving. Now, if it is the case that a correspondence between image displacement and 0 movement is a necessary condition for position constancy, then the absence of such a correspondence should lead to the loss of position constancy and the appearance of movement in the visual field. Since the afterimage does not displace, the afterimage should appear to move when the 0 moves.One might summarize this view of position constancy by saying that retinal image displacements are evaluated in terms of the available information about 0 movements so that a correspondence between image displacement and 0 movements will always lead to position constancy and conversely a lack of correspondence, retinal displacement in a noncorresponding direction or at a noncorresponding rate, or the absence of any retinal displacement at all coupled with 0 movement will always lead to the appearance of object movement. The perception of an afterimage during eye movement is quite analogous to Emmert's Law in the case of size perception. If the diminishing size of the image is taken into account in perceiving size as constant at increasing distances, then a nonchanging image must be seen as changingsize with increasing distance.Some qualifications: The evidence now indicates that the information about eye position and eye movement is derived from signals corollary to those going to the eye muscles rather than from proprioceptive feedback from the eye muscles (Brindley & Merton, 1960). Thus, where "there is no efferent information that the eyes have been directed to move and there is image displacement-as in the case of a passively pushed eye viewing a normal scene-no transference of the displacement "energy" occurs-and the scene will appear to jump. An afterimage, however, viewed under the same condition should appear stationary, for there is neither efferent information about eye movement nor image displacement.3

An investigation of the relationship between eye and retinal image movement in the perception of movement

“…If this were the case, then, since no retinal displacements would be registered during an eye movement, there would be no reason to expect a loss of position constancy during eye movements, and there would be no reason to postulate some kind of comparator that could match retinal displacement to 0 movement information. That this cannot be the case may be seen from the fact that there is evidence that an afterimage appears to move even when it is viewed in complete darkness and the only 0 movement is 0 eye movement (Mack & Bachant, 1969). This suggests that at least the absence of any retinal displacement during an eye movement constitutes a baSis for movement perception.…”

Apparent motion of stimuli presented stroboscopically during pursuit movement of the eye

“…This assumption is made explicitly by Koffka (1935). Bruell and Albee (1955), Walls (1951), Rock and Ebenholtz (1962), Gregory (1958), and Mack and Bachant (1969), and implicitly by many others. It has long been known (Dodge, 1906), however, that the pursuit is a distinctly different eye movement from the saccade, and recently gathered evidence (Rashbass, 1967) indicates that different brain centers may be involved in the control of each type of eye movement.…”

“…Almost all theories (Helmholtz 1866; Hering, 1879; James, 1890;Sherrington, 1918;Koffka, 1935;Bruell & Albee, 1955;Walls, 1951;von Holst, 1954;Rock & Ebenholtz, 1962;Mack & BacHant, 1969) seem' to agree that image motion produced by saccadic eye movemen ts somehow is cancelled by the taking-into·account process. 2 These theories will be referred to here as cancellation theories.…”

Induced motion of a fixated target: Influence of voluntary eye deviation

“…Thus, the wrist of the right hand was already hyperextended toward the right when the rod was gripped without any slant, giving an attenuated range of wrist motion in this direction (in response to leftward stimulation), compared with the range available for leftward wrist rotation (in response to rightward stimulation). Other studies in which the plane of rod rotation was normal to a frontal plane have found no effect of stimulus direction (Heck- curring with afterimages and imaginary targets is consistent with this identity, since pursuit itself is similarly effective with afterimages (Mack & Bachant, 1969) and during imaginary and predicted target motions (Steinbach, 1976;Whittaker & Eaholtz, 1982). A predictive component of nystagmus suppression has also been detected (Larsby, Hyden, & Odqvist, 1984).…”