In a Neuroimage article, Martens et al. (2018) write:

“The perceptual process view sees expertise as a stimulus-driven, domain-general process, with expertise-related neural changes located in one specific region that encompasses the type of processing necessary for expert object recognition (Gauthier and Tarr, 1997). The expertise hypothesis, a more specific version, focuses on the relation between expertise and face processing. According to this hypothesis, FFA is the brain region in which “expert processing” takes place (Gauthier et al., 2000, 1999).” p.91.

This is an incorrect portraying of the expertise account discussed in these articles (or any that I have authored). Martens et al. seem to assume that we are looking for an answer to the question “where in the brain does expertise activate?”, to which we answer “the FFA”. But in reality, these studies of ours asked the specific question “What explains face-selectivity in the FFA?” to which we answered “Expertise individuating faces”. Accordingly, the expertise account of the specialization for faces in FFA does not propose that the same mechanisms account for selectivity in all brain areas that are face-selective, nor that all objects of expertise should engage the FFA, nor that the FFA is the only area that should be recruited by objects of expertise. Consulting the rest of our work on expertise in different domains, or comparing expertise with different tasks, should make this really clear. Other aspects of expertise, including the acquisition of non-visual semantic information or domain-specific skills involved in different kinds of expertise (e.g., reading musical notation or playing chess), are bound to engage a host of brain systems. For instance, in Martens et  al. (2018), activation in experts who know the name of items is compared to activation in novices who do not know these names. Effects of expertise in the frontal lobe could very well reflect that naming – in any case, these effects are irrelevant to the expertise account of specialization in the FFA.

Martens, F., Bulthé, J., van Vliet, C., & de Beeck, H. O. (2018). Domain-general and domain-specific neural changes underlying visual expertise. NeuroImage, 169, 80-93.

The Vanderbilt Holistic Face Processing Test (VHPT-F)
Jennifer J. Richler, R. Jackie Floyd, Chao-Chih Wang, David Ross and Isabel Gauthier
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The Vanderbilt Face Matching Test
Mackenzie Sunday, Jennifer J. Richler and Isabel Gauthier
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Learned Attention in an object-based frame of reference
Kao-Wei Chua and Isabel Gauthier
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Cortical thickness in fusiform face area predicts face and object recognition performance
Rankin W. McGugin, Ana E. Van Gulick and Isabel Gauthier
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Harel, Kravitz and Baker recently published an article in Frontiers in Human Neuroscience (2013), Beyond perceptual expertise: revisiting the neural substrates of expert object recognition, which was also a poster at VSS (May19th, 2014).

This is an opinion piece, and I believe that authors are entitled to their opinions, and that debate is generally good for progress in a field. However, under the pretense of proposing a novel framework (see Wong & Wong’s commentary on the article for an explanation that this is not in fact a novel framework), the authors have severely mis-represented the literature on expertise. Next year, at VSS, we will be celebrating the 30^th meeting of the Perceptual Expertise Network: so I know this field, and I do not recognize it in the picture painted by Harel et al.

My point here is not to dispute the claims made in the paper. I find it more appropriate to do in empirical demonstrations, such as in this recent paper. Rather, I want to state that my views (and of course those of my co-authors) are misrepresented in this article. I could say ”misunderstood”, but after having discussed this with the first author, and going back to the literature record to make sure that I am not completely wrong about my own work, I think misrepresentation is a fair term.(this is probably too strong, Harel et al. swear they really thought these were appropriate representations of my/our ideas). And I do not believe that such distortion leads to clear debate that is generally good for a field. It is in nobody’s interest that people becoming interested in the study of expertise would be provided with such a distorted picture of the field. I embrace people disagreeing with my views, but only when they are really my views.

Let me focus on two main points:

1. “…attaining any form of visual expertise should be supported primarily by qualitative changes in processing within specific regions of visual cortex (Palmeri and Gauthier, 2004).”

Overall, in this paper (and others by the same authors) as well as in the poster, what we are being associated with is a simplistic theory, something like the main effect of “expertise” (any kind) is changes in one area (the FFA).

This is a strawman we would not want to be associated with. Let me emphasize this:

I would not argue that expertise with all categories are the same behaviorally, nor in the brain.

You will find evidence of this across all these articles:

• James, K. H., James, T. W., Jobard, G., Wong, C.-N., Gauthier, I. (2005). Letter processing in the visual system: different patterns for single letters and strings, Cognitive and Affective Behavioral Neuroscience, 5(4): 452-66. PDF
• James, K.H., Gauthier, I. (2006). Letter Processing automatically recruits a multimodal brain network, Neuropsychologia, 44(14):2937-49. PDF
• Wong, C.-N, Gauthier, I. (2007). An analysis of letter expertise in a levels-of-categorization framework, Visual Cognition, 15(7): 854-879. PDF
• Wong, A.C.-N., Jobard, G., James, K.H., James, T.W., Gauthier,I. (2009). Expertise with characters in alphabetic and non-alphabetic writing systems engage overlapping occipito-temporal areas, Cognitive Neuropsychology, 26(1), 111-127.PDF
• Wong, Y.K., Gauthier, I. (2010). A multimodal neural network recruited by expertise with musical notation. Journal of Cognitive Neuroscience, 22(4), 695-713.PDF
• Wong, A. C.-N., Palmeri, T. J., Gauthier, I. (2009). Conditions for face-like expertise with objects: Becoming a Ziggerin expert – but which type? Psychological Science, 20(9): 1108-1117. PDF
• Wong, A.C.-N., Palmeri, T.J., Rogers, B.P., Gore, J.C., Gauthier, I. (2009). Beyond shape: How you learn about objects affects how they are represented in visual cortex, PLoS One, 2(12), e8405.PDF
• Wong, Y. K., Folstein, J. R., & Gauthier, I. (2012). The nature of experience determines object representations in the visual system. Journal of Experimental Psychology: General. 141(4):682-698. PDF

Second, I do not believe that the primary result of expertise is necessarily selectivity in the FFA.

 I started my career asking why faces appeared to be special in specific ways. Why do they show holistic processing? Why do they engage the FFA? These are questions that some of our research specifically addresses. When trying to test the claim that faces are special because of a specific effect, it is more than appropriate to look at that effect/area. By showing that there is no clear dissociation (between faces and objects of expertise) in that effect/area, you address that specific claim. That’s it. It doesn’t make any prediction about expertise not having other behavioral or neural effects.

 Have we published studies focusing on the FFA’s role in expertise? For sure! But these particular papers address a very strong claim that is not ours: One that suggests face perception is “a cognitive function with its own private piece of real estate in the brain” (Kanwisher, 2000; 2010).  If there is a claim here that is “face-centric”, or “FFA-centric”, it is that original claim, which we are challenging.

Importantly, we have not only addressed this question. We have reported, starting in 1999 in our work on Greeble expertise, and in 2000 in our work on car and bird experts, other areas than the FFA that show expertise effects. We have continued to do so for different kinds of expertise since then (see papers cited above).

2.” …expert processing under this perceptual view is automatic and stimulus- driven, with little impact of attentional, task demands or other higher-level cognitive factors (Tarr and Gauthier, 2000; Palmeri et al., 2004).

The Wong & Wong commentary on the Harel et al. paper does a good job of outlining how those of us who have been studying perceptual expertise for years have been looking both at the automatization of processing with expertise, and have studied the interaction of perception with high-level factors.

For recent examples: our work on selectivity for musical note expertise (Wong et al., in press) specifically focuses on the influence of top-down influences; In Wong, Folstein & Gauthier (2012), where we compare perceptual expertise and perceptual learning, we discuss how experience interacts with attentional set to determine the pattern of training effects in the brain; and in McGugin et al., (2012), we discuss the possibility that semantic knowledge interacts with perceptual expertise to lead to a more bilateral representation.

Instead of calling those of us who have been studying expertise for more than 15 years “face-centric”, Harel et al. could have actually covered some of the work we (and others) have done that already goes well beyond faces and FFA. Instead they focused only on those papers that specifically address the theory that “FFA is a unique face module”, and ended up presenting a very skewed view of what this field has been all about.

I waited a while before “greebling” about this one – but Harel and colleagues seem intent on framing their own contributions against this face-centric view of the perceptual expertise literature. I am sending them the link to this clarification, and I hope that they stop misrepresenting my contributions as face-centric. If you have opinions about this, one way or another, I have posted a comment on the Wong & Wong opinion on the Frontiers web site, you can add yours.

References without links:

Kanwisher N (2000) Domain specificity in face perception. Nat Neurosci 3:759–763

Kanwisher, N. (2010). Functional specificity in the human brain: a window into the functional architecture of the mind. PNAS, 107(25), 11163-11170.

Rezlescu, Barton, Pitcher & Duchaine  (RBPD) recently published an article in PNAS, presenting evidence that two patients with acquired prosopagnosia were able to become “Greeble experts”. RBPD argue that this refutes a fundamental prediction of the expertise hypothesis.

Although it is always interesting to hear about what specific patient can and cannot do, I would argue we cannot learn much that is compelling from this evidence. I was asked to comment on the article by Andreas von Bubnoff, a journalist for Nature News (see his coverage), but since my comments will likely be greatly abbreviated, I thought I would elaborate here.

Not an actual prediction.
RBPD argue that a “fundamental prediction” of the expertise hypothesis is that people with prosopagnosia should also be impaired at acquiring expertise for other objects. Although at first glance this may sound right, it is incorrect. The expertise account proposes that the reason we observe specialization for faces in behavior and in the brain is due to a specific kind of experience with faces. Or, to state it more specifically: if you have to individuate non-face objects that are visually similar and you use the same strategy most people use to learn faces, then the same kind of specialization may occur for non-face objects.

The qualifications are important, because expertise is not ONE thing. Expertise is just becoming really good in a given domain that was difficult to start with. My colleagues and I have published a considerable amount of work in which we show that how you become an expert constrains the kind of expert you become (e.g., McGugin et al., 2011; Wong et al., 2012; Wong et al., 2009a). Clearly one can become an expert in non-face domains, like cars, and recruit the face area (McGugin et al., 2012; in press; Xu, 2005) and in other domains, like print or musical notation, and engage other brain areas (e.g., Wong et al., 2009b; Wong et al., 2012). How you become an expert is likely to depend on a number of factors, including the information available in the stimuli, the task you are trying to perform, whatever biases you may bring to the situation, and what strategies are available to you.

This last point about strategies is really important to interpret RBPD’s new article. They used a procedure that was designed to elicit a specific strategy—holistic processing— in normal subjects, but their argument depends on the assumption that this is the only strategy one could use. We may be responsible for this misconception in not being sufficiently clear in our early work. However, our work with prosopagnosic patient LR (Bukach et al., 2012), who also became a Greeble expert like the patients in RBPD’s article, is very clear on this point. Because each Greeble has unique parts, there is no principled reason one has to use holistic processing in a Greeble training study. The fact that normal subjects seem to adopt a holistic processing strategy does not speak to what patients would do if integrating across parts is not easy for them. By testing controls and patient LR’s processing of Greebles that did not have unique parts after training, we were able to show that similar performance can come from different strategies. This was not verified by RBPD about their patients, so we cannot know whether their processing of Greebles is holistic and normal, just that their performance individuating Greebles is as good as controls.

Suggesting that Greebles and faces are somehow equated.
The critical evidence in RBPD’s article is that the patients can learn Greebles and not faces. Thus, whether the two tasks are equated is important. In their abstract, they called the face procedure “matched” to the Greeble task. But their description makes it clear that they selected faces to be highly similar, whereas they did not do the same for Greebles. They used 20 Greebles during training, 4 Greebles from each family (apparently 2 from each gender, defined by all parts pointing up or down), which means that each Greeble in the experiment only had a single similar foil (another Greeble with the same body shape and direction of parts). The original Greeble set used in the first Greeble training study (Gauthier & Tarr, 1997) and in the work with patient LR (Bukach et al., 2012) used a more difficult set with 30 Greebles (2 similar foils per object). The faces RBPD used are more homogenous than the Greebles on any metric we can think of (this is obvious from their figure).

Imagine that the deficit in prosopagnosia has to do with a difficulty integrating across parts of an object. Integrating across parts will be particularly useful when the local featural information is not very diagnostic. Nobody predicts that RBPD’s patients should have difficulty processing the overall body shape of these objects or the direction of their parts. Thus, the Greeble task requires RBPD’s patients to learn to distinguish each Greeble from a single foil, and this can be done by looking at a single part, say the top right appendage (because all Greebles have unique parts). In contrast, the Face task could be performed based on single parts but each face has 19 other similar foils). These two tasks are not matched in difficulty. This is apparent when you consider that the control subjects, who have had a lifetime of experience with faces and no experience with Greebles, did equally well at learning greebles as they did faces.

These properties should not be taken as limitations of the Greebles or the Greeble training procedure. These were designed on purpose to be easier than faces, as a much simplified reduced “world” in which a limited amount of training might be able to produce holistic processing and FFA activity. The training itself is a manipulation and was not designed as a test of any kind. Being able to learn the Greebles was never supposed to be a test of whether someone is using face-like processing (although how a patient may learn them might be telling, Bukach et al., 2012).

Bukach, C.M., Gauthier, I., Tarr, M.J., Kadlec, H., Barth, S., Ryan, E., Turpin, J.  & Bub, D. (2012). Does acquisition of expertise in prosopagnosia rule of out a domain-general deficit?, Neuropsychologia, 50(2): 289-304.

Gauthier, I., & Tarr, M.J. (1997). Becoming a “Greeble” expert: Exploring mechanisms for face recognition, Vision Research, 37(12), 1673-1682.

McGugin, R.W., Van Gulick, A.E., Tamber-Rosenau, B.J., Ross, D.A. & Gauthier, I. (in press). Expertise effects in face selective areas are robust to clutter and diverted attention but not to competition. Cerebral Cortex.

McGugin, R.W., Gatenby, Gore, J.C.,Gauthier, I. (2012). High-resolution imaging of expertise reveals reliable object selectivity in the FFA related to perceptual performance. Proceedings of the National Academy of Sciences, 109(42), 17063-17068.

McGugin, R.W., Tanaka, J.W., Lebrecht, S., Tarr, M.J., & Gauthier, I. (2011). Race-Specific perceptual discrimination improvement following short individuation training with faces. Cognitive Science, 35(2):330-47.

Wong, A. C.-N., Palmeri, T. J., Gauthier, I. (2009a). Conditions for face-like expertise with objects: Becoming a Ziggerin expert – but which type? Psychological Science. 20(9), 1108-17.

Wong, A.C.-N., Jobard, G., James, K.H., James, T.W., & Gauthier, I. (2009b). Expertise with characters in alphabetic and non-alphabetic writing systems engage overlapping occipito-temporal areas. Cognitive Neuropsychology, 26(1): 111-127.

Wong, Y.K., Folstein, J.R., & Gauthier, I. (2012). The nature of experience determines object representations in the visual system. Journal of Experimental Psychology: General, 141(4):662-98.

Wong, Y.K. & Gauthier, I. (2012). Music-reading expertise alters visual spatial resolution for musical notation, Psychonomic Bulletin and Review, 19(4):594-600.

Xu, Y. (2005). Revisiting the role of the fusiform face area in visual expertise.Cerebral Cortex, 15(8), 1234-1242.