Friday, August 18, 2006

On the Detection of Agency and Intentionality in Nature

AUTHOR: Elena Broaddus

SOURCE: Evolution and Design

COMMENTARY: Allen MacNeill

First, many thanks to the faithful readers who have also continued to pay attention to the Evolution and Design website (the weblog of the "notorious Cornell evolution and design seminar" and the contents contained therein. I am particularly pleased that the hard work and careful thought of the students whose papers have been posted has been recognized, and even moreso that they have been given the highest praise possible: that is, critical analysis.

I would like to draw some more attention to E. Broaddus paper on the “innate” tendency to infer purpose in nature. I have long suspected that humans (and perhaps many vertebrates, especially mammals) have this tendency. As an evolutionary psychologist, I at least partially subscribe to the idea that the human mind is composed primarily of “modules” whose functions are to process particular kinds of sensory information in such a way as to yield adaptive responses to complex environmental information. This is precisely what Broaddus argues for in her paper: that the human mind (and, by extension, the vertebrate “mind” in general) has a module that is adapted specifically for the precise and rapid inference of intentionality in nature. That such an “agency detector” (to use the commonly accepted term for such a module) would have immense adaptive value is obvious. In an environment in which other entities do indeed have “intentions” (i.e. predators, competitors, potential mates, etc.), the ability to detect and infer the possible consequences of acting upon such intentions would confer immense adaptive value on any organism with such an ability.

Furthermore, as Broaddus points out (and as we discussed briefly in the seminar), to be most effective such a detector should be tuned in such a way as to detect virtually all such “intention-indicating” behaviors. This would have the effect of producing a significant number of “false positives,” as any detector that is tuned high enough to detect all actual cases would have such a side-effect.

As Broaddus points out, one of the side-effects of such an “agency detector” would be the detection of intentionality in entities that clearly had no such intentions. If, for example, one of the most important functions of such a detector in humans is to quickly “read” and assess the intentions betrayed in human facial expressions, then it would almost certainly detect human facial expressions in objects in the environment that clearly do not have such expressions, such as rocks, foliage, water stains, etc. This would explain the ability of many humans to “see” human facial expressions in such things as water stains, cinnamon buns, rocks, etc.

Clearly, there are some “natural objects” that do, indeed, have human facial expressions impressed upon them: the faces of the presidents at Mount Rushmore are an example cited ad nauseam by ID theorists. However, I am much more interested in “faces” that humans detect in rocks and other environmental objects that are clearly not produced by human agency. Indeed, the faces at Mount Rushmore constitute a kind of “control” for this ability, as they are clearly the result of intentionality, and therefore can be used to anchor that end of the “agency detection” spectrum (at the other end of which are things like “faces” in clouds, tree foliage, etc.). Somewhere in this spectrum is a cross-over point at which actual intentionality/agency disappears and facticious intentionality/agency takes over. It is the location of that cross-over point that constitutes the hinge of the argument between evolutionary biologists and ID theorists.

Broaddus’s analysis of autism as a possible example of malfunctioning “agency detection” is, IMO, brilliant, and presents an immediately testable hypothesis: that autistic children lack well-tuned “agency detectors,” and that this at least partially explains their well-known indifference to intentional agents, such as other people (including their parents), animals, etc. In people with both full-blown autism and the milder Asperger’s syndrome (sometimes called Aspies”), a common attribute is an impaired ability to infer intentionality (or, in many cases, the mere existence of other minds) on the part of autistics and Aspies. As Broaddus points out, there are clear anatomical and functional differences between autistics, Aspies, and non-impaired people, and that these differences may be correlated with the etiology of these conditions. For example, it is very interesting that there appears to be more (rather than less) neurons in the brains of autistics than in non-impaired people.

This lends credence to the generally accepted hypothesis that the information processing “modules” proposed by evolutionary psychologists are the result of “pared down” neural networks that are speciallized for particular cognitive tasks. Clearly, the agency/intentionality detector in humans functions extremely well and, as the parlance goes, “in the background.” We are rarely conscious of its operation, despite the fact that it is virtually always “on.” This explains, for example, something I first noticed as a young child: that no matter how much I tried, I couldn’t NOT see faces in the patterns in the linoleum on the floor of my grandmother’s kitchen, in the foliage of trees, in rocks, and in photographs of billowing smoke, splashing water, etc. The agency/intentionality detector works extremely efficiently in people of all ages, but especially in children. Indeed, as Broaddus points out, part of becoming an adult consists in learning (usually by trial-and-error) which of the seemingly intentional entities which we perceive all the time actually are intentional agents and actually have intentions vis-a vis ourselves. We must learn, in other words, to critically analyze the constant stream of “positive” agency/intentionality detection events, and discriminate between those that affect us and those that do not. It may be that this discrimination process actually involves the neurological “re-wiring” of the parts of the sensory/nervous system that produces such detection events, and this might explain, at least in part, the decreased ability of adults to believe in the existence of intentional agents in the natural environment.

Broaddus not only presents a cogent hypothesis concerning the existence of such an agency/intentionality detector/module in humans, she proposes several possible ways of testing whether or not such a detector actually exists, and to “map” its dimensions, capabilities, biases, and limitations. I believe that this opens up a very fruitful area of empirical research into such detectors, and can ultimately lead to much more clarity about an issue that so far has generated much more heat than light. I hope that her ideas and suggestions will be followed up by others (I certainly intend to do so), and that further empirical research into this fascinating and little-known capability will add to our understanding of what makes us the peculiar creatures we are.

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Thursday, August 03, 2006

Follow-up Post on Analogies in Science

In comment # 20 in a thread at, PvM said:

"ID relies on the concept of analogy to infer design. Science does the hard work to provide mechanisms, pathways and provides analyses of the data to support their conclusions. That’s the big difference. How do we know an analogy really exists?"

This was precisely my point in my blogpost on identity and analogy (see
For example, do we have any objective way to determine if one rock is analogous with another? Or whether an anatomical feature (or a protein/substrate binding site) is analogous to another? As in the case of telology, we think we can do this very easily (just as we can easily identify what looks like design), but I would argue that this is because both "finding" analogies and "finding" design/purpose are capabilities of the human mind/nervous system that have conferred enormous adaptive value on our ancestors. As in the case of our putative innate "agency/design/purpose detector" (which first becomes active in very early infancy), our "analogy detector" also appears to become active at a very early age, and operates entirely "in the background." That is to say, we are almost totally unaware of its operation, and concentrate only on its output.

Our ability to detect (and construct) analogies is probably the core of our "intelligence," as demonstrated by the fact that identifying analogies has been traditionally used as one of the most sensitive guages of general intelligence (i.e. "g") in intelligence tests (such as the Miller Analogies Test). As more than one participant in this thread has pointed out (Sal, I think you were first), doing mathematics is essentially the construction of highly compact analogies, in which numerical (and sometimes physical) relationships are expressed as abstract symbols.

Interestingly, in the case of some analogies in biological systems we have an independent double-check on our identification of analogous things. This is based on the evolutionary concept of homology, or derivation from a common ancestor. If two structures on two different organisms (say a small bone of the jaw of a reptile and the even smaller bone in the middle ear of a mammal) appear to be analogous (on the basis of size, location, relationship to other bones, etc.) there are at least two different, though related, methods of verifying that these structures are indeed analogous (and not just accidentally similar). One way is by means of comparative paleoanatomy, in which a series of fossils of known age are compared to determine if there is a connection between the evolutionary pathways of derivation of the structures. If such a pathway can be empirically shown to exist, this would be strong evidence for both the analogous and homologous nature of the objects. Alternatively one could compare the nucleotide sequences that code for the structures to determine if they are sufficiently similar to warrant a conclusion of homologous derivation. In both cases, evidence for homology, combined with our intuitive "identification" of analogous structure and/or function, both point to the same conclusion: that the two structures are both analogous and homologous.

BTW, this is why structures that appear to be analogous, but for which there is no convincing evidence of homology (as in the wings of birds and insects) can present a serious problem to evolutionary biologists, and especially systematists/taxonomists and those engaged in cladistic analysis. Such apparent similarities (technically called homoplasies) can either be the result of "true" (i.e. partial) analogy at the functional (and/or structural) level (and therefore assumed to be the result of convergent evolution) or they can be completely accidental. Simple inspection can be insufficient to separate these two hypotheses, and lacking either fossil or genomic evidence, conclusions about actual analogy can be extremely difficult to draw. However, if there is fossil and/or genomic evidence and it points away from homology (i.e. descent from a common ancestor), then the structures can be considered to be analogous but not homologous.

In the same comment, PvM also wrote:

"I also think that Sal is overusing the concept of analogy to mean almost anything."

Indeed, it is essential in discussions such as these that we be as precise as possible about our definitions, as imprecision can only lead to confusion (at best) and unsupportable conclusions (at worst). Perhaps the most essential distinction to be made in this regard is between "anaologies of description" (which could also be called "semantic analogies") and "analogies of function/structure" (which could also be called "natural analogies"). The former (i.e. "semantic analogies") are merely artifacts of the structure of human cognition and language, as happens whenever we describe an analogy that we have perceived. By contrast, the latter (i.e. "natural analogies") are the actual similarities in function/structure that we are describing (i.e. that resulted in our identification and description in the first place). As in the Zen koan about the roshi and the novice in the moonlit garden, much of the confusion about which of the two types of analogies we are discussing seems to stem from confusion between the moon that illuminates the garden and the finger pointing at the moon.

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