Dark Matter of the Mind

by Daniel L. Everett

  Other researchers became interested in Pirahã perception after hearing that the Pirahãs seemed to be unable to recognize even pictures of themselves. Thus in a collaborative effort, Mike Frank, Ted Gibson, and I conducted a number of experiments among the Pirahãs in 2007 (in cooperation with the coauthors of Yoon, Winawer, et al. 2007). We reached several important conclusions, summarizing our findings thus:

  A core principle of vision science is that perception is not simply a passive reflection of the external world, but a process of constructive interpretation of inherently ambiguous input. Consider a shadow projected onto a wall. The same silhouette can be created by different objects of different sizes at different distances from the viewer. Images projected onto the retina have the same inherent ambiguity, and a wide range of perceptual judgments ranging from lightness (Adelson 1993), to color, to depth, to shape and identity, are the result of “unconscious inferences” by the visual system (Helmholtz 1878). Such inferences are often presumed to be automatic and culturally universal (Gregory 2005; Kohler 1929; Spelke 1990). (Yoon, Whitthoft, et al. 2014, 1)

  As we interpret the world around us, the problem is not seeing the details, but putting together what we are seeing into coherent percept, or gestalt. This “putting together” occurs effortlessly and without awareness. What we see are the etics of vision. The gestalt, the interpretation, the connecting the dots of what we perceive is emic vision. Properly emicized, we see the whole “better”—seeing things that are not there and not seeing things that are. For example, consider the two-tone ocelot in figure 4.1 (right column, second row from the top).2 People often fail to recognize the two-tone image; when shown the corresponding photograph, however, they find the two-tone often transforms suddenly into a coherent percept. Are they using emic knowledge to interpret etic images, or are they simply getting better information, unconnected to outsider or insider knowledge? Observers viewing the ocelot in the two-tone will often make figure-ground errors, incorrectly assigning some background regions to the figure, some figure regions to the background. Reconfiguring figure-ground assignments after viewing the photograph is to “reorganize” one’s initial grouping to achieve a different perceptual state (Kovacs and Eisenberg 2004). If the viewer ultimately recognizes the previously unrecognized image, perception reorganization is said to have been successful.3

  Figure 4.1

  It is not the case that all images we see—even degraded two-tone ones—require access to full cultural knowledge or require perceptual reorganization. For example, advertisers work to develop symbols, “logos,” that the average person of most cultures (especially Western cultures) can recognize early, even when they are two-toned (e.g., the World Wildlife Fund’s panda logo). Similarly, some simple black-and-white line drawings are immediately recognizable. At the same time, it is possible to construct two-tone images that are difficult to perceive from the emic perspective. Interestingly, however, when such images are presented with the corresponding full photo cue, they readily trigger perceptual reorganization (Dolan et al. 1997; Hsieh, Vul, and Kanwisher 2010; Ludmer, Dudai, and Rubin 2011).

  The question that motivated this research project was whether principles underlying perceptual organization are universal. We know that there is evidence that very young infants and remote cultures show certain principles of perceptual (re)organization (Pica et al. 2011; Spelke 1990). And we also find a body of evidence that there is variable susceptibility to phenomena across different populations. This kind of variability, infant studies not withstanding, suggest an important role for culturally variable factors in perception. For example, there is evidence that experience with photographs (Segall, Campbell, and Herskovits 1966), digital clocks (Whitaker and McGraw 2000), culture-specific processing biases (de Fockert et al. 2007), and exposure to urban vs. rural vistas (Leibowitz et al. 1969; for a review of older work, see Jones and Hagan 1980) all produce different abilities of perceptual organization in the relevant domains.

  All researchers agree that culturally invariant mechanisms of development such as the physiological maturation of the visual system ought to produce perceptual differences between children and adults. But children may also become more strongly enculturated into the practices of perceptual inference and interpretation accepted in their particular community over time, similarly predicting differences in how children and adults perceive the world (Vygotsky 1978). For example, a particularly striking phenomenon in perceptual development is the deficient recognition of two-tone images in young children. This is in spite of the fact that adults recognize them easily (Kovacs and Eisenberg 2004; Yoon, Winauer, et al. 2007). When faced with images like figure 4.1 (even ones containing familiar creatures), children—like adults—often struggle to recognize the animal. Significantly, however, children have much greater difficulty recognizing the animal even when the two-tone image is placed side by side with the original picture.

  An important question that arises in the present discussion, then, is whether the perceptual reorganization reported by adults results from their perceptual maturation, or whether it is the result of dark matter acquired in specific cultural contexts (and particular individual histories). This was the motivation for my and my coauthors’ interest in experiments concerning the Pirahãs. Like young children in a modern industrial culture, Pirahã adults have little experience or knowledge of the visual transformation that links a photo with a two-tone image. On the other hand, Pirahã adults do possess both physiologically mature visual systems and a lifetime of experience with complex visual tasks, such as hunting and fishing.

  In our experiments, we tested Pirahã adults and English-speaking controls on their ability to recognize two-tone images given the corresponding photographs as cues (fig 4.1). My own prediction was that, like children and US adults, the Pirahãs would have difficulty recognizing two-tone images. In fact, we all believed that if expertise in interpreting symbolic visual materials is a key factor in photo-cued two-tone reorganization, then the Pirahã—like children but unlike US adults—would have trouble recognizing the cued image even in the presence of the photo.4 For the experiments, my coauthors used Photoshop to create ten two-tone images by blurring and posterizing (reducing the number of distinct grayscale values, in this case to two: black and white) grayscale photographs of animals and individuals found in the Pirahã participants’ everyday environment (fig. 4.1).5 We additionally tested two other image pairs that did not include two-tones and for which the correspondence was easier to see (fig. 4.2).6 We used these to get Pirahãs engaged and warmed up and to make sure that they understood what we were asking them to do.

  Figure 4.2

  Each trial proceeded in three stages. In stage 1, participants were shown a two-tone image and asked to indicate their recognition by pointing to the location of the eye or Pirahã person in the picture (fig. 4.2). Responses were marked by placing a sticker at the indicated locations. Trials in which the target was not initially identified were considered “candidate reorganization trials.” These trials were of particular interest, as they provided a test of whether an initially unrecognized two-tone image could be successfully reinterpreted after seeing the corresponding photo. These trials proceeded to stages 2 and 3. In stage 2, participants were shown the corresponding photograph alone and asked to point to the location of the eye or Pirahã person. In stage 3, the two-tone image and photograph were shown side by side. The experimenter then pointed back and forth between the two images using the Pirahã word for “same” to convey the correspondence between photo and two-tone. After this instruction, the subject was again asked to point to the location of the eyes or the person in the two-tone image. I held most of the pictures about a foot and a half to three feet from each subject. This slight variation is unlikely to have had any significant effect. In a separate control study to test for the possibility that close viewing interfered with perceptual reorganization, US adults viewed two-tones from a much closer viewing distance than seen in any participants (nine inches
) and performed at ceiling on candidate reorganization trials (100 percent). In addition, US preschoolers, a similarly low reorganization population, viewed two-tones from distances of two and four feet with no difference in performance (Yoon, 2012).

  My colleagues also tested Stanford students on an alignment manipulation task. This task controlled for the possibility that US participants’ performance on the task was not due to recognizing the two-tone images, but merely to locating the point on the two-tone card in the same location as the corresponding point in the photograph. This study was identical to the main study, except that the images were cropped by 10 percent on two adjacent sides (e.g., top and left), chosen at random, with the constraint that the corresponding two-tone and photo were not cropped on the same two sides. (An example is shown below in fig. 4.4). Thus the eye or head was in a different location on the printed card in the photo and in the two-tone. If US participants were solving the task by pointing to the same location on the cards rather than by identifying the image features in the two-tone image, they would not have successfully located the eye in the two-tone image in this experiment.

  As stated in Yoon, Whitthoft, et al. (2014):

  Pirahã participants and U.S. control participants on the same task successfully indicated the target locations (either eye or person) on the non-two-tone practice images without the corresponding photo cue (controls 100%, Pirahã 88.9%), showing participants understood the task (Figure 3, white bars [fig. 4.3 in this volume7]). Controls located the targets successfully in uncued two-tone images on 72.5% of trials. Initial recognition in Pirahã participants was less frequent (22.5% of trials). Controls identified the targets in the corresponding, untransformed photos 100% of the time and the Pirahã 90.3% of the time (Figure 3, black bars). All Pirahã participants correctly indicated the target on at least 7 of the 10 photos. Data from trials where the Pirahã did not correctly recognize the photo were excluded from subsequent analysis.8

  Figure 4.3

  What we were most interested in is termed candidate reorganization trials. These were cases in which the participants in our study failed to initially locate the target in the two-tone (incorrect stage 1), but did locate it when presented with the photo (correct stage 2). We next calculated the percentage of two-tones recognized after viewing the photo and then dividing by the total number of these trials. Interestingly, our US controls consistently demonstrated the ability to reorganize what they were perceiving, by accurately recognizing the eye or the Pirahã person on previously unrecognized two-tones. Pirahã participants, on the other, hand succeeded on such reorganization trials only 31.6 percent of the time. In fact, two Pirahã participants never were able to perceive the content of the two-tone images. The best recognition performance that any Pirahã achieved was 60 percent. Thus, what we did in these experiments was to test whether Pirahãs were able to perceptually reorganize two-tone images when they were viewing the latter along with the original (unphotoshopped) photos. US participants performed nearly perfectly. The Pirahãs, on the other hand, struggled. The contrast was striking.

  The question that we get to then is why this recognition and perceptual reorganization task was so much harder for the Pirahãs. There are a couple of potential explanations for our findings. These include how well the Pirahãs understood the task, their familiarity with the stimuli they were asked to judge, and the difficulty of the task. After deciding what it was that we were observing, our next step was to consider the range of possible differences in perception and discuss possible conceptual or experiential sources of differences in the groups’ perceptual reorganization.

  We determined that US adults are accurate at detecting the correspondence between photos and corresponding photoshopped two-tone images even when the images no longer share a predictable coordinate frame relative to one another (e.g., as in fig. 4.4).9 This means that the US adults had to use emic understanding of the concept of two-dimensional representations—that is, perceptual reorganization—in order to identify the unpredictably displaced location in the two-tone image within the figure. We accounted for the US vs. Pirahã performance differences in terms of “perceptual literacy,” attributing to Pirahã and US performance differences to cultural differences in training and education with visual symbolic materials.

  Figure 4.4

  Our data are incompatible with the idea that the Pirahãs did not understand the task. The Pirahãs’ excellent performance on the practice trials and on the photos themselves demonstrates that the Pirahã understood the general task instructions. As we ran the experiments, we were careful, both verbally and gesturally, to indicate that the photo and two-tone images were of “the same” subject, using the Pirahã phrase ai sigíai, “the same.” On the other hand, suppose that Pirahã participants did not know how to interpret the experimenter’s instructions. Nevertheless, they would have understood that the photo and two-tone images corresponded once they had correctly interpreted the two-tone image. Yet this is not what we found; success in one trial did not increase accuracy on subsequent trials. This indicates that even when recognizing a picture, there was no emic knowledge of two-dimensional space interpretation (these are my words, not those of my coauthors). Moreover, since the photographs we used were of people and animals the Pirahãs knew their performance, it is also unlikely that the result is due to a lack of familiarity with the pictured items. In fact, the Pirahãs knew the items, fauna, and people better than the US control subjects.

  The kind of two-tone image recognition we experimented with could, of course, be missed for other reasons. Another possibility is that the Pirahãs are not able to do hard mental work. My experience with the Pirahãs’ learning of math, emic understanding of their environment, ability to predict my behavior, and so on, contradicts that possibility. The Pirahãs inability on the two-dimensional tasks—like mine on seeing dangerous animals in the forest—simply shows that a mature visual system is insufficient to guarantee recognition of what one sees. The mature system “sees” only the etic until it has undergone emicization into a particular culture, with particular experiences, expectations, and so on.

  US citizens need to acquire an emic recognition of two-dimensional representations because these are ubiquitous and crucial sources of information in their cultures, because they are schooled for years in such recognition, and because society places a high value on this type of seeing ability. In other words, there is such a thing as emic understanding of perceptual experiences that ranges beyond the merely physical and etic limitations of the ocular nerve.

  As we noted in our study, “One prediction of this account is that participants’ degree of cultural ubiquity and expertise with decoding visual symbolic materials should relate to their degree of ease and automaticity using visual cues to interpret ambiguous and impoverished images.” And this is what we find, at least for the phenomena investigated.

  Culture is essential for even seeing the world around us. Sights begin as etic experiences and are eventually turned into components of emic understanding. We are born like the blind man who told Jesus, “I see men as trees walking.” There are therefore implications of the idea that dark matter is our hermeneutic, even for basic perception. We receive input far beyond our capacity to attend to it. Noise is noise, after all, because we decide it is not part of a message, or not part of what we are attending to at a given moment. Illusions, optical and aural, occur because we attend to incorrect cues, believing falsely that they are relevant to the inpretation or perception of the entity, thought, sound, and so in in focus (Rock, Hall, and Davis 1994). Individual experience and culture (what is relevant, what is known, etc.) are easily the most important components of our perceptual cognition. And they guide us because we have moved from an etic perspective to an emic one, embedded the perceptual categories and strategies into ourselves as unspoken material of reasoning.

  Beyond Counterexamples and Exceptions: Dark Matter and Science

  As a final example of the lessons of this chapter,
I want to examine the notions of “counterexample” and “exception” in scientific research, in order to demonstrate the reach of culture and dark matter into this hallowed domain, beginning with a familiar form of argument, the syllogism. So consider the following statements:

  All swans are white.

  Johnny is a swan.

  Johnny is white.

  But what if Johnny is not white? What if Johnny is a black swan? This is a case that “All swans are white” cannot account for. Do we reject “All swans are white,” or do we have to reject the idea that Johnny’s blackness is relevant for the statement that “All swans are white?” What if Johnny had just rolled in black crude oil? Surely that would be superficially a violation of “All swans are white” but not worth abandoning the syllogism. Somehow we have the intuition that if the swan is black because it rolled in oil, then there is no violation of “All swans are white,” though if the swan is black because it is born that way, then there is a violation. But even this is simplistic. What if the swan that was born black had a genetic anomaly of some sort?

  Ultimately a black swan is evaluated relative to a cultural system. For some, a black swan will be an innocuous exception. For others, it will be a devastating counterexample. This cultural interpretation of exceptions vs. counterexamples is important to the central thesis of this book, because it gets at the very heart of the scientific enterprise that is the centerpiece of many modern societies. Science, we might say, ought to be exempt from dark matter. Yet that is much harder to claim than to demonstrate.

  Throughout the course of this book, we have considered different approaches to the science of Homo sapiens, what binds us together, our marvelously group-individual psyches, and the ways in which business, culture, psychology, textual understanding, translation, the formation of linguistic systems, and so on, are functions of dark matter and the role of emicization in forming individual psyches to an understanding of aspects of the sociology of science. Science is among the highest attainments of some civilizations. Not all societies value it, though every society feels its effects, from the isolated, uncontacted Amazonian tribe being filmed from the air by drone to the religious fanatics decrying science while driving pickups. And scientists—like other intellectuals, businesspeople, extreme athletes, or in fact the members of any community—are subject to the formation of dark matter that can affect their work qua scientists without them being fully aware of it. Moreover, this subtle, invisible hand in scholarship has lessons that epitomize the thesis of this book and the applications of this thesis to life.