Forgive the lengthy quotations below. It will take a while to build up to Roland Barthes’s studium and punctum. (I explain my recent interest in allure here.) In the ninth section of Camera Lucida (1980), Barthes writes:
I was glancing through an illustrated magazine. A photograph made me pause. Nothing very extraordinary: the (photographic) banality of a rebellion in Nicaragua: a ruined street, two helmeted soldiers on patrol; behind them, two nuns. Did this photograph please me? Interest me? Intrigue me? Not even. Simply, it existed (for me). I understood at once that its existence (its “adventure”) derived from the co-presence of two discontinuous elements, heterogeneous in that they did not belong to the same world (no need to proceed to the point of contrast): the soldiers and the nuns. (23, bold added)
Here is the image Barthes describes:

He continues, “I foresaw a structural rule (conforming to my own observation), and I immediately tried to verify it by inspecting other photographs by the same reporter (the Dutchman Koen Wessing): many of them attracted me because they included this kind of duality which I had just become aware of.” Barthes then provides one photographic description after another:

Here a mother and daughter sob over the father’s arrest (Baudelaire: “the emphatic truth of gesture in the great circumstances of life” ), and this happens out in the countryside (where could they have learned the news? for whom are these gestures?). Here, on a torn-up pavement, a child’s corpse under a white sheet [see right]; parents and friends stand around it, desolate: a banal enough scene, unfortunately, but I noted certain interferences: the corpse’s one bare foot, the sheet carried by the weeping mother (why this sheet?), a woman in the background, probably a friend, holding a handkerchief to her nose. Here again, in a bombed-out apartment, the huge eyes of two little boys, one’s shirt raised over his little belly (the excess of those eyes disturb the scene). And here, finally, leaning against the wall of a house, three Sandinists, the lower part of their faces covered by a rag (stench? secrecy? I have no idea, knowing nothing of the realities of guerrilla warfare); one of them holds a gun that rests on his thigh (I can see his nails); but his other hand is stretched out, open, as if he were explaining and demonstrating something. My [structural] rule [of discontinuous duality] applied all the more closely in that other pictures from the same reportage were less interesting to me; they were fine shots, they expressed the dignity and horror of rebellion, but in my eyes they bore no mark or sign: their homogeneity remained cultural: they were “scenes,” rather à la Greuze, had it not been for the harshness of the subject. (23-25, bold added)
What makes these Wessing photographs more interesting than others “from the same reportage”? What sort of dual structure serves as the condition of the allure that captures an excess over and above the “harshness of the subject” represented? Barthes continues his theoretical meditations in the tenth section:
My rule [of discontinuous duality] was plausible enough for me to try to name (as I would need to do) these two elements whose co-presence established, it seemed, the particular interest I took in [Wessing’s] photographs. (25)
It is worth remarking that “the particular interest”—the generation of allure, a lure to feeling (as Alfred North Whitehead might put it)—needs both of the elements Barthes is on the verge of defining. Reading on:
The first [element], obviously, is an extent, it has the extension of a field, which I perceive quite familiarly as a consequence of my knowledge, my culture [what Jonathan Culler might call “my [pictorial? visual?] competency”]; this field can be more or less stylized, more or less successful, depending on the photographer’s skill or luck, but it always refers to a classical body of information: rebellion, Nicaragua, and all the signs of both: wretched un-uniformed soldiers, ruined streets, corpses, grief, the sun, and the heavy-lidded Indian eyes. Thousands of photographs consist of this field [those of Wessing and many others], and in these photographs I can, of course, take a kind of general interest, one that is even stirred sometimes, but in regard to them my emotion requires the rational intermediary of an ethical and political culture [represented, one might surmise, in the photograph itself?]. What I feel about these photographs derives from an average affect, almost from a certain training. I did not know a French word which might account for this kind of human interest, but I believe this word exists in Latin: it is studium, which doesn’t mean, at least not immediately, “study,” but application to a thing, taste for someone, a kind of general, enthusiastic commitment, of course, but without special acuity. It is by studium that I am interested in so many photographs, whether I receive them as political testimony or enjoy them as good historical scenes: for it is culturally (this connotation is present in studium) that I participate in the figures, the faces, the gestures, the settings, the actions. (25-26, bold added)
Barthes is feeling his way through the dark here, but in my own shorthand I summarize / paraphrase his insight thus: the studium is that to which I am culturally trained to respond. It constitutes the field of photographed things I am already ready to see, think, feel, like, dislike, and judge by virtue of the fact that I am an enculturated being, trained to be a particular sort of ethical, political creature among other creatures. Later in Camera Lucida, Barthes writes, “The studium is that very wide field [remember: it is ‘an extent’] of unconcerned desire, of various [passing?] interest, of inconsequential taste” (27). Face-to-face with the studium, the viewer encounters “the photographer’s intentions” and undergoes a “a kind of education” in “knowledge and civility, ‘politeness'” (27-28). My interest—Barthes admits—may be piqued, since “I am interested in the world” in general; but the studium does not inspire “love” (41). Rather, it piques my “sovereign consciousness,” which “invest[s] the field of the studium” as a thing I (can) know, recognize, and judge (26).
But what of the second element, the one that truly makes “[p]hotography . . . subversive” (38)? Back to the original passage:
The second [structural] element will break (or punctuate) the studium. This time it is not I who seek it out (as I invest the field of the studium with my sovereign consciousness), it is this element which rises from the scene, shoots out of it like an arrow, and pierces me. A Latin word exists to designate this wound, this prick, this mark made by a pointed instrument: the word suits me all the better in that it also refers to the notion of punctuation, and because the photographs I am speaking of are in effect punctuated, sometimes even speckled with these sensitive points; precisely, these marks, these wounds are so many points. This second element which will disturb the studium I shall therefore call punctum, for punctum is also: sting, speck, cut, little hole—and also a cast of the dice. A photograph’s punctum is that accident which pricks me (but also bruises me, is poignant to me). (26-27)
The punctum is a “detail” for which I am not prepared—”a partial object” that imposes itself (or seems to impose itself) on the photographic field suddenly and violently (43). It expands metonymically; it “has, more or less potentially, a power of expansion” (44). It “attracts me,” a silent conqueror of vision (42). Barthes tries out a few more phrases to capture this “strange thing,” co-present with the studium (49). The punctum is “an intense immobility” (49). It shows us our “incapacity to name” the unexpected, uncanny thing (51). Paradoxically, “it is what I add to the photograph and what is nonetheless already there” (55).
What do you see? What were you not prepared to see?
No analysis prepares me to see the punctum of a photograph; I encounter it, quite simply, as an “accident” in excess of the photographer’s skill or intention or control (27). It is “given right there on the page”; “I . . . receive it right here in my eyes” (42-43). It has an immediate hereness. It requires the studium—that which is “clear” to me (43)—in order to emerge, but it emerges unbounded by “morality or good taste” (43); it is an “ill-bred” (43), purposeless instance of “grace” (45): a visual “gift” for which I did not ask (45). It is, I suggest, the lure of allure; the snare hidden by no one beneath or amidst the studium, which is itself the ruse of familiarity, recognition, and belonging. For photographic allure to be alluring, it requires a co-presence of familiarity and unexpectedness that blurs agency, that introduces paradox and encounter into the field of vision and thought, that seduces me into loving nothing/something (no one has intended the punctum). What sort of dance of vision, of affect, of attraction is this?
Reading on . . .