Sartre’s movement-imagery investigations

Sartre’s movement-imagery investigations use finger movements, visual attention, and touch to examine how an image takes shape through bodily activity. Their decisive finding is that a movement can present a visual figure without being experienced as a kinaesthetic figure: the image is neither a retinal copy nor simply an effect produced by a consciously perceived muscular sensation. The experiments make bodily movement a means through which consciousness constitutes an imagined form, while also clarifying the difference between perceiving a movement and imagining what it traces.

Experimental Setup and the Moving Finger

Sartre begins from a proposed sequence for some mental images: an idea of a movement is followed by a muscular attitude that gives the motor intention an objective form, without the subject noticing that attitude as such; an image then arises in consciousness as a registration of the motor reaction, qualitatively different from the reaction itself. He considers earlier explanations, including Dwelshauvers’s, insufficient, and turns to the experiences themselves to clarify how the sequence works.

In one demonstration, the eyes remain open while Sartre looks at the index finger of his right hand as it traces curves and geometrical figures in the air. The finger’s changing positions do not appear merely as a set of isolated visual presents. Retinal persistence leaves a faint trail where the finger has just been, but the successive positions are also bound together by synthetic acts that give the movement continuity. Drawing on Edmund Husserl’s account of retention and protention, Sartre describes consciousness as holding on to the just-vanished phase while anticipating what is about to follow. These acts are not themselves images; they organize the present sensation in relation to the movement’s immediate past and expected continuation.

What those temporal intentions ultimately organize is not a row of sensations but the trajectory of the finger. The path already covered can appear as a vague luminous trace, while the path still to be covered is anticipated beyond the finger’s current position. Visual impressions establish this form, accompanied by weaker sensations from the skin, muscles, tendons, and joints. Those kinaesthetic sensations support the experience, but remain subordinate to vision and are quickly effaced rather than persisting as an independent motor image.

The Closed-Eye Figure and the Image’s Status

The result changes when Sartre closes his eyes and repeats comparable movements with his finger. Removing visual input does not make the kinaesthetic sensations vivid or dominant; the kinaesthetic sensation also disappears. What emerges instead is a trajectory in the process of formation. When the fingertip traces a figure of eight, the figure appears as it is being drawn, like letters forming on a cinema screen. It is located at the fingertip, but it appears as a visual figure, not as a kinaesthetic one.

Sartre argues that this figure is not supplied by visual sensation, since the eyes are closed. It is presented as the visual form that could be seen at the fingertip if the eyes opened: a figure as imaged. Nor, he contends, does the movement simply evoke an image while remaining unconscious. That explanation would require the kinaesthetic sensations both to persist alongside the image and to cause it, yet efforts to recover those sensations make the image disappear. The image can also persist briefly after the movement has stopped, seeming to remain where the finger moved. Its duration therefore cannot be reduced to the ongoing presence of a muscular impression.

The experiment tests how an imagined path can be constituted through movement without identifying the path with the bodily sensations that accompany it. In Sartre’s account, the image is apprehended at the fingertip, while the movement’s kinaesthetic elements lose their independence within the imaging activity. This distinction lets him treat movement as part of the image’s formation without reducing the image to a sensation or to an effect mechanically triggered by movement.

Planned Movement, Touch, and Sketchy Tracing

Sartre distinguishes chance movements, where knowledge and movement arise together, from movements whose form is known in advance. In a planned gesture, initial knowledge is vague; as anticipated phases become retained phases, it becomes more precise and gives direction to the movement. When Sartre deliberately traces a figure of eight, the movement thus makes prior knowledge explicit. The form can be attended to as a static spatial figure, as the concrete impression that makes it actual, or through an intermediate experience in which a moving body brings the form from potentiality to actuality.

The analysis also applies to passive perception: a figure traced by another person on a subject’s palm or cheek can be visualized even though the subject does not see the tracing. In a small investigation, Sartre asks a subject to identify a form drawn on the palm with the subject’s eyes closed. One answer identifies a Z and describes seeing the form at the tip of Sartre’s index finger. The report connects the tactile tracing to a visualized figure at the moving fingertip, rather than to a purely tactile outline.

A fully executed movement is not always necessary. When a subject already knows which figure will be traced, a brief or subdued motor indication may suffice. Sartre explains such sketchy movements through the temporal structure of movement-consciousness: even a very brief real movement can divide knowledge into an orientation toward the past, which retains, and an orientation toward the future, which anticipates. The reduced gesture is therefore not simply an incomplete version of a full tracing; it can provide the minimal sensible moment through which an already known form acquires temporal direction.

From Bodily Tracing to Schematic Figures

Sartre’s account of finger tracing belongs to a wider analysis of how movement organizes images and schematic drawings. A face-like schema may first appear as disconnected marks: three line segments, an isolated point, and a sinuous line. Under a different intention, those marks can be read as a forehead, eyebrow, nose, eye, mouth, and chin. The change is not accomplished by the lines alone. The viewer’s eyes move in determinate ways, and the body helps enact the missing connection between separate marks. The blank sheet is reorganized as well: space to one side functions as a solid region, while the other side recedes as ground or void.

This differs from perceptual figures, which can impose movements on the eyes and make their directions seem like real qualities of the perceived object. In the Müller-Lyer illusion, for example, the closed angles arrest eye movement while the open angles permit it to continue; the opposed movements are attributed to the line segments, which appear to possess extension or force. Sartre contrasts this perceptual organization with schematic imagery: the schema does not itself prescribe the movement in the same way. Knowledge guides the eye, and its spontaneous movements are projected as imaged directions. If a figure crystallizes, the viewer can see a running man in the marks while remaining aware that the movement has been freely projected onto them.

The comparison clarifies what the finger experiments are meant to establish. Movement can participate in constituting a figure, but its role depends on the attitude through which the figure is apprehended. Sartre also points to work by Wolfgang Köhler, Max Wertheimer, and Kurt Koffka as a basis for studying how formal structures persist through changes of position and help explain why perception includes more than is immediately seen. In both schematic drawing and movement tracing, the organized figure cannot be understood by treating its parts as isolated sensory contents.

Theoretical Reach and Artistic Analogue

The movement investigations support a broader distinction between a real material carrier and an imagined object constituted through it. In his discussion of art, Sartre applies this distinction to painting: the canvas, frame, and paint are real, but the depicted aesthetic object is not simply identical with those materials. It appears when consciousness takes an imaging attitude toward the canvas. The painter constructs a material analogon through which an irreality can be apprehended; the imaginary object is not thereby realized as a real thing.

Sartre extends the account to fiction and performance. Words can function as analogues for imagined objects, while an actor’s body, gestures, and feelings can serve as analogues for Hamlet without the actor literally positing himself as Hamlet. These examples do not turn the finger-tracing exercise into an account of artistic production. They show the wider reach of the same problem: how a real movement or material medium can make an image accessible while remaining distinct from the imagined object it helps present. In that framework, bodily movement is not merely an external accompaniment to imaging; it is one of the concrete routes through which an image can be formed and apprehended without becoming a perception of a real object.