Time course of face processing: the N170

 Get a pdf of an extended version of our research program on the N170 (updated July 2015)

The general goal of our research is to clarify the mechanisms of face recognition in the human brain. Event-Related Potentials (ERPs) recorded on the human scalp can be particularly informative for this goal. Because of their excellent time resolution, ERPs can help tracking perceptual face processes as they unfold through time.

The sudden onset (flash) of a face stimulus elicits a particularly large negative component on the adult huma, most prominent onoccipito-temporal sites, peaking at about 170 ms. This component has been named the N170 in the seminal study of Bentin and colleagues (1996), which was the first study to focus on this component and in which several experiments were performed to characterize its response properties. The N170 is clearly related to the  conscious perception / interpretation of a visual stimulus as a face, as we argued in this review (Rossion, 2014).

We have been studying this component in the lab for almost 20 years (first papers published in 1999; e.g., Rossion et al., 1999), and have more than 30 publications on this component ( see full list here , and below). In a nutshell, our research has investigated a number of issues with the N170:

- We  showed that the N170 and the ealier described Vertex Positive Potential (VPP) by Jeffreys (1989) reflect opposite sides of the same generators, varying inversely in amplitude with the location of the reference electrode on the scalp (Joyce & Rossion, 2005).

- We provided evidence that the N170 onset marks the earliest time-point (on the scalp, and with this approach of flashing stimuli) of face-selectivity that cannot be accounted for by low-level visual cues. In contrast, early sensitivity to faces at the elevel of the P1 component is accounted for by low-level visual cues (Rossion & Caharel, 2011).

- We reported large effects of competition between 2 faces (Jacques & Rossion, 2006) or between faces and objects of expertise (Rossion et al., 2004; Rossion et al., 2007) using an original design in which stimuli are presented concurrently.

- We provided evidence that the N170 amplitude is largely modulated by spatial attention, but that this effect is independent of competition between faces (Jacques & Rossion, 2007).

- We showed that pictures of different kinds of objects also elicit a N170 component, with varying amplitudes Rossion et al., 2000, although the N170 is larger for faces (this is discussed in another review: Rossion & Jacques, 2008).

- We found that the N170 is reduced in amplitude if the same face identity is repeated immediately, an effect that resists changes of size, but not inversion, and is thus not accounted for by low-level visual cues (Jacques et al., 2007). This identity-adaptation effect has been replicated in many studies of our group, showing for instance that it resists changes of viewpoint up to 30 degrees rotation (Caharel et al., 2009; Caharel et al. 2011; Caharel et al., 2015), and is due mainly to shape rather than texture/colour information (Caharel, Jiang et al., 2009).

- We demonstrated that early individualization of faces (N170) is based on a holistic representation, using the composite face illusion  (Jacques, & Rossion, 2009; Kuefner et al., 2010).

- Recorded N170/P170 components in the right ocicpitl face area of a single patient implanted intracerebrally (Jonas et al., 2012; Jonas et al., 2014)

All these studies are better described in our research program on the N170

see also our review chapter: Rossion, B. & Jacques, C. (2011). The N170 : understanding the time-course of face perception in the human brain. To appear in The Oxford Handbook of ERP Components (2011), Edited by S. Luck and E. Kappenman. Oxford University Press.

Any comment about this text? Please email  bruno.rossion@uclo uvain.be. 

 

Related Papers/Abstracts


Caharel, S., Collet, K., & Rossion, B. (2015). The early visual encoding of a face (N170) is viewpoint-dependent: a parametric ERP-adaptation study. Biological Psychology, 106, 18-27. [PDF]

Jonas, J., Rossion, B., Krieg, J., Koessler, L., Colnat-Coulbois, S., Maillard, L., Frismand, S., Colnat-Coulbois, S., Vignal, J.-P., Vespignani, H., Jacques, C., Brissart, H., Maillard, L. (2014). Intracerebral electrical stimulation of a face-selective area in the right inferior occipital cortex impairs individual face discrimination. NeuroImage, 99, 487-497. [PDF] [videos]

REVIEW Rossion, B. (2014). Understanding face perception by means of human electrophysiology. Trends in Cognitive Sciences, 18, 310-318. [PDF]

Caharel, S., Ramon, M., Rossion, B. (2014). Face familiarity decisions take 200ms in the human brain: electrophysiological evidence from a go/no-go speeded task. Journal of Cognitive Neuroscience, 26, 81-95. [PDF]

Jonas, J., Descoins, M., Koessler, L., Colnat-Coulbois, S., Sauvee, M., Guye, M., Vignal, J-P., Vespignani, H., Rossion, B., Maillard, L. (2012). Focal electrical intracerebral stimulation of a face-sensitive area causes transient prosopagnosia. Neuroscience, 222, 281-288. [PDF] [video 1] [video 2]

Kovács, G.,  Zimmer, M., Volberg, G., Lavric, I., Rossion, B. (2013). Electrophysiological correlates of visual adaptation and sensory competition. Neuropsychologia, 51, 1488-1496. [PDF]

Rossion, B. & Caharel, S. (2011). ERP evidence for the speed of face categorization in the human brain: disentangling the contribution of low-level visual cues from face perception. Vision Research, 51, 1297-1311 [PDF]

  • This is a study that we should have completed a long time ago … It is fairly simple. We stimulated with faces, cars, and their respective phase-scrambled versions (phase-scrambled faces and phase-scrambled cars). Pictures of faces and cars were equalized for luminance but were left deliberately uncontrolled for other potential differences in power spectrum and color. We replicated both the larger P1 and N170 to faces than cars. However, the P1 face effect was equally large for phase-scrambled stimuli: it was larger for phase-scrambled faces than phase-scrambled cars, even though these stimuli could not be perceived as meaningful categories at all. In contrast, the N170 face effect was found only for non-scrambled versions of the stimuli. This study shows that even if a preferential response to faces can be found before the N170 onset, namely during the P1 timewindow, it should not be interpreted as reflecting the perception of a face.

Alonso-Prieto, E.A., Caharel, S., Henson, R., Rossion, B. (2011). Early (N170/M170) face-sensitivity despite right lateral occipital brain damage in acquired prosopagnosia. Front. Hum. Neurosci. 5:138. doi: 10.3389/fnhum.2011.00138 [PDF]

  • We report a face-sensitive N170 effect over the right hemisphere of the prosopagnosic patient PS, despite extensive damage in this hemisphere and no evidence of right OFA activation in numerous previous studies. The N170 also shows the amplitude increase and delay to inverted faces. A M170 is also disclosed in a MEG study. Interestingly, the component is absent in the left hemisphere, where she has another lesion in the middle fusiform gyrus (no left FFA). This observation suggests that the OFA is not necessary to observe early sensitivity to faces in the right occipito-temporal cortex.

Caharel, S., Jacques, C., d'Arripe, O., Ramon, M., & Rossion, B. (2011). Early electrophysiological correlates of adaptation to personally familiar and unfamiliar faces across viewpoint changes. Brain Research, 1387: 85-98. [PDF]

  • We previously found that a N170 face identity adaptation effect over right electrode sites even when the adapter and target faces are presented under different viewpoints (Caharel et al., 2009a). Here we hypothesized that it would increase when presenting pictures of personally familiar faces. This would have provided evidence that the behavioral advantage provided by familiarity in individual face matching was related to perceptual encoding. Instead, we found that the effect disappeared for familiar faces: the N170 was no longer different in amplitude for repeated and unrepeated face identities! Interestingly though, an effect appeared on the left hemisphere N170 for familiar faces. At much later latencies, closer to the behavioral response, we found a larger effect for familiar than unfamiliar face.

Kuefner, D., de Heering, A., Jacques, C., Palmero-Soler, E., Rossion, B. (2010). Early visually evoked electrophysiological responses over the human brain (P1, N170) show stable patterns of face-sensitivity from 4 years to adulthood. Frontiers in Human Neuroscience. 3:67. doi:10.3389/neuro.09.067.2009 [PDF]

  • A study in which we show that the P1 and N170 do not change specifically for faces between 4 years of age and adulthood, contrary to what was stated in previous studies. There are indeed major changes in the basic response properties of these components (reduction of latency and amplitude, lateralization of posterior topography), but they are found for any kind of visual stimulus for the P1, and for both faces and objects (cars) for the N170. A larger N170 for faces than cars, with a right lateralization, is found in younger children and does not appear to increase with age.

Kuefner, D., Jacques, C., Prieto, E.A., Rossion, B. (2010). Electrophysiological correlates of the composite face illusion: disentangling perceptual and decisional components of holistic face processing in the human brain. Brain and Cognition, 74, 225-238. [PDF]

  • Here we used the composite face effect, a well-known measure of holistic face perception, in combination with an oddball paradigm in ERPs and a Go/Nogo response, asking participants to detect rare changes of identity to the top halves (but ignore changes to the bottom halves). Our idea was to show that even when human observers do NOT respond behaviorally to changes of identity on the bottom halves of faces, and do not elicit a lateralized readiness potential (LRP), there is an electrophysiological marker of holistic face perception in the sense of a larger N170 to these trials (relative to the repetition of the exact same face, see Jacques & Rossion, 2009). It seems quite obvious to me (and many researchers) that the composite effect reflects a perceptual effect, but strangely enough some authors have argued that its locus is decisional, based on behavioral data. The present study provides direct evidence against this claim.

Jacques, C., Rossion, B. (2010). Misaligning face halves increases and delays the N170 specifically for upright faces: implications for the nature of early face representations. Brain Research, 1318, 96-109. [PDF]

  • Don’t get confused … This study is not really about the composite face effect, which is an effect that reflects the perception of individual faces and that was tested in another study (Jacques & Rossion, 2009). Here we extended the study of Letourneau & Mitchell (2008), by testing the effect of misaligning horizontally the two halves of face (top and bottom). We replicated their observation that this misalignment (paradoxically) increases the latency and the amplitude of the N170, particularly in the right hemisphere, just like inversion. But we used several control conditions to show that this observation cannot be accounted for by a general effect of spatial misalignment of visual patterns. Interestingly, we also found that it does not hold for inverted faces. These observations support the view that the early face representation activated in the human brain at the level of the N170, is that of a global upright face pattern.

Caharel, S., Jiang, F., Blanz, V., Rossion, B. (2009). Recognizing an individual face: 3D shape contributes earlier than 2D surface reflectance information. NeuroImage, 47, 1809-1818. [PDF]

  • A very clear and interesting finding to me, illustrating nicely the interest of the ERP approach. We used our identity adaptation paradigm, but manipulated the kind of information that conveyed the identity of the face: either 3D shape, or 2D surface reflectance (color/texture), or both simultaneously. Behaviorally, participants discriminated faces better and faster when the two kinds of information were present, as in previous studies. However, ERP data told a different story: at the level of the N170, a significantly larger amplitude than the repeated face identity condition was found only when 3D shape differed between the adapter and target face. When surface reflectance alone was different, there was no significant effect. However, at a later component (P2), shape and reflectance elicited an effect of the same magnitude, while combining the two kinds of diagnostic information elicited the largest effect (in line with behavior). Hence, the early encoding of an individual face percept seems to be based primarily on 3D shape, not surface reflectance.

Jacques, C., Rossion, B. (2009). The initial representation of individual faces in the right occipito-temporal cortex is holistic: electrophysiological evidence from the composite face illusion. Journal of Vision, 9(6):8, 1–16. [PDF]

  • Here the identity adaptation paradigm was used to test the hypothesis that as early as the individual face was perceptually encoded (N170 peak, see Jacques et al., 2007, JOV), this encoding is holistic. Observers fixated the top halves of two sequential faces to match. We found that even when the bottom halves only changed identity, eliciting the visual illusion of a change on the fixated top half, the N170 was larger in amplitude than when there was no change of identity. This effect disappeared if the two halves were spatially misaligned. This study therefore demonstrates that the first individual face representation that is perceived is holistic rather than based on independently perceived local part

 

Caharel, S., d'Arripe, O., Ramon, M., Jacques, C., Rossion, B. (2009). Early adaptation to unfamiliar faces across viewpoint changes in the right hemisphere: evidence from the N170 ERP component. Neuropsychologia, 47, 639-643. [PDF]

  • We asked whether the larger N170 to unrepeated compared to immediately repeated faces would still hold despite a change of viewpoint between the two faces. One previous study suggested that it was not the case, but we were not convinced by an absence of effect and used a sensitive paradigm with long duration of presentation for the adapter and a short delay before the presentation of the target face. Even across a 30° change of viewpoint, there was still an identity adaptation effect, but only on the right N170 

 

Maurer, U., Rossion, B., McCandliss, B. (2008). Category specificity in early perception: face and word N170 responses differ in both lateralization and habituation properties. Frontiers in Human Neuroscience, 2:18. [PDF]

  • This study directly contrasted N170 responses to words and faces within the same subjects, examining both category-level habituation and lateralization effects. ERP responses to a series of different faces and words were collected under two contexts: blocks that alternated faces and words vs. pure blocks of a single category designed to induce category-level habituation. Global and occipito-temporal measures of N170 amplitude demonstrated an interaction between category (words, faces) and block context (alternating categories, same category). N170 amplitude demonstrated class-level habituation for faces but not words. Furthermore, the pure block context diminished the right-lateralization of the face N170, pointing to class-level habituation as a factor that might drive inconsistencies in findings of right-lateralization across different paradigms. No analogous effect for the word N170 was found, suggesting category specificity for this form of habituation. Taken together, topographic and habituation effects suggest distinct forms of perceptual processing drive the face N170 and the visual word form N170.

Rossion, B. & Jacques, C. (2008). Does physical interstimulus variance account for early electrophysiological face sensitive responses in the human brain? Ten lessons on the N170. NeuroImage, 39, 1959-1979. [PDF]

  • REVIEW.  This long paper was written in reaction to a terrible paper published in Nature Neuroscience by Thierry and colleagues, in which the authors claimed that the larger N170 to faces than other visual stimuli was due to a methodological uncontrolled artifact in previous studies. Our long “10 lessons” paper was written after several groups of N170 researchers were denied by the journal the right to publish independent responses, and that these authors did not acknowledge their mistake in their reply. Some of my colleagues tend to say that Thierry et al.’s paper in Nature Neuroscience, even if it was incorrect, was only “controversial”, or “useful”, as a methodological warning for instance. From my part, I believe that this paper was not controversial, or useful in any way. It was wrong. Plainly wrong. Everything was wrong about it: the fact that authors who had no knowledge about this area of research and the N170 in particular could publish such a poor quality paper (in a so-called “high profile” journal), their deliberate ignorance of the existing literature that contradicted their nonsense claim, the measure of the N170 at wrong electrode sites to make sure that it would not be larger for faces than objects, the lack of explanation for a P1 effect, and the disrespectful attitude of the authors in their paper and their reply about other people’s work. It is an area of research that is confusing enough and does not need such papers, raising uninteresting debates. Anyway, I admit that our own paper was written with a feeling of frustration, which you can certainly sense in the review paper here. But at least it allowed this false problem created by Thierry et al. to be buried immediately. Our paper provided us with the opportunity to make a number of points regarding the functional interpretation of the N170, and I hope that in the end it makes a useful contribution to the research in this area.

Bentin, S., Taylor, M.J. Rousselet, G.A., Itier, R.J., Caldara, R., Schyns, P.G., Jacques, C. & Rossion, B. (2007). Much ado about nothing: controlling interstimulus perceptual variance does not abolish N170 face sensitivity, Nature Neuroscience, 10, 801-802. [PDF] [+ supplementary figures 1 2 3 4]

  • A very frustrating experience. Following the publication of the terrible paper by Thierry et al. in Nature Neuroscience, several groups of researchers experienced with the N170 complained to the journal and wrote replies. The editors acknowledge that a response should be granted, but forced all researchers to write a single 600 words common reply. This requested quite a lot of work and coordination, and prevented the authors to develop the full arguments to explain why Thierry et al.’s paper had to be entirely dismissed. Also Thierry et al. were granted a reply, in which they tried to hide the limitations of their original study further and claimed that there were no rules in the field according to which some electrodes should be used to measure the N170 appropriately. This whole thing made me determined to write something more extensive, hence the “10 lessons” review paper above, in order to explain why that paper was wrong, and what lessons could be drawn from such an unfortunate publication.

Jacques, C. & Rossion, B. (2007). Early electrophysiological responses to multiple face orientations correlate with individual discrimination performance in humans. NeuroImage, 36, 863-876. [PDF]

  • We aimed at understanding whether the N170 variations with inversion were meaningful with respect to the face inversion effect. We presented face stimuli at 12 orientations, from 0° to 330°, during a face identity matching task. ERP analysis was made on the first stimulus, and behavioral measures on the second (target) stimulus. The results show that the variations of amplitude with stimulus rotation at he level of the P1 do not present the same pattern as the behavioral measures. However, after the P1, in the rising slope of the N170, one starts to see the same pattern emerging, with a “M”-shaped function across orientations both for behavior and EEG amplitude. The study suggests that the face inversion effect takes place at perceptual encoding, but not before the N170 time-window.

Jacques, C. & Rossion, B. (2007). Electrophysiological evidence for temporal dissociation between spatial attention and sensory competition during human face processing. Cerebral Cortex, 17, 1055-1065. [PDF]

  • In two studies (Rossion et al., 2004; 2007) summarized below, we found that when an expert with fixates a nonface object of expertise (Greebles or cars, respectively), the N170 in response to a face is significantly reduced in amplitude. Unsurprisingly, opponents of the expertise hypothesis claimed that this was merely an effect of attention: experts would pay more attention to their object of expertise than novices, therefore leading to a reduced N170 to faces. We had (many) reasons to believe that it was not correct, but we decided to tackle this issue directly. Here, we found that if you increase attention to the center, the N170 to a lateralized face is indeed reduced in amplitude, but this effects is additive to the reduction observed when it is a face that is fixated instead of a scrambled face. Most importantly, attention reduces not only the N170 but also the P1, while the competition effect (face vs. face compared to face vs. scrambled) concerns the N170 only. These findings suggest that the effect of visual expertise on the N170 in response to faces are not due to attention.

Rossion, B., Collins, D., Goffaux, V., Curran, T. (2007). Long-term expertise with artificial objects increases visual competition with early face categorization processes. Journal of Cognitive Neuroscience, 19, 543 - 555. [PDF] [slideshow summary] [draft in color]

  • An extension of the study by Rossion et al. (2004) on visual expertise in the context of a visual competition paradigm. This study also shows one of the clearest effect of visual expertise with nonface objects on the perceptual encoding of faces, this time with large sample of participants (20 car experts, 20 novices). If you are busy fixating the picture of a car, the appearance of a face on the right or left of the car (which remains there) leads to a N170. This N170 is largely reduced in amplitude if you are a car expert as compared to a novice, particularly in the right hemisphere, suggesting that the perceptual encoding of the face suffers from the visual competition created by the fixation of the car picture. No difference is found between novices and experts if they fixate a cross or a non-recognizable pixellated car. We also show that this effect almost disappears if the car picture is removed before the appearance of the face, indicating that concurrent visual stimulation is critical to get a large effect. Irrespective of your interpretation of these findings (and attention is not a valid candidate, see Jacques & Rossion, 2007, Cerebral Cortex), while studies on visual expertise have been criticized for the small and non-replicable effects that they often report, this one truly reports big effects, in a simple paradigm.

Jacques, C. d'Arripe, O., Rossion, B. (2007). The time course of the inversion effect during individual face discrimination. Journal of Vision,

7(8):3, 1-9, https://journalofvision.org/7/8/3/, doi:10.1167/7.8.3. [PDF]

  • If you present a face and then the same face again, we show that the N170 is reduced in amplitude (compared to a condition in which a new face is presented). Previous studies had found such effects but they were usually weak or not the focus of the study. Moreover, many studies fail to report face identity repetition effects on the N170. The interest of the present study is that we get a clear and large effect by increasing the duration of the first stimulus (several seconds), as in behavioral adaptation studies, and by using a very small ISI duration. We also change the size between the first and second stimulus of a pair, to remove pixelwise adaptation effects. Most importantly, we show for the first time that this effect is not present if the exact same faces are presented upside-down. We conclude that during the time-window of the N170, there is enough information accumulated by the system to be able to individualize faces.

Jacques, C. & Rossion, B. (2006). The speed of individual face categorization. Psychological Science,17, 485-492. [PDF]

  • In this study, we introduced an original stimulation paradigm: we presented a continuous train of two faces alternating with each other at about 1.66 Hz. The rate was not fixed (duration of each face stimulus varied between 500 and 700 ms). Replacing a face by another face this way, without inserting a baseline, allowed us to almost cancel out the event-related responses that were not related to the difference between the 2 faces. This way, we erased the P1. We found a first negative deflection peaking at the exact same latency and topography as the N170, showing that individualization of faces takes place already at that latency. Using morphing, we also found that the response was larger when the 2 faces crossed a perceptual category boundary than when they remained within the same boundary (physical distance between the faces of the 2 pairs being equal).

Jacques, C. & Rossion, B. (2006). The time course of visual competition to the presentation of centrally fixated faces. Journal of Vision, 6, 154-162. [PDF]

  • This is a follow-up study to Jacques & Rossion (2004, Neuroreport). Here we show that the decrease of the N170 amplitude while processing a face can be observed even for stimuli that are presented at the fovea.

Joyce, C.A., Schyns, P.G., Gosselin, F., Cottrell, G.W., Rossion, B. (2006). Early selection of diagnostic facial information in the human visual cortex. Vision Research, 46, 800-813. [PDF] [slideshow summary]

  • In this study, we wanted to show that the N170 amplitude could be modulated by the task at hand, providing that the diagnostic information for this task is presented to the observer. We used the response classification images (and their inverse, non-diagnostic features) of “Bubbles” for gender and expression tasks, and asked observers to perform either of the two tasks. The N170 was larger for the difference between diagnostic and no-diagnostic features. This effect was indeed modulated (slightly) by the task at hand: if you have to categorize a face for expression, this difference is larger for diagnostic – non-diagnostic cues for expression than for gender, and vice-versa. Despite a strong manipulation and clear behavioral effects, the N170 effects were not very large though, showing that the N170 amplitude is largely, although not completely, unaffected by the task at hand.

Joyce, C. A. & Rossion, B. (2005). The face-sensitive N170 and VPP components manifest the same brain processes: The effect of reference electrode site. Clinical Neurophysiology, 116, 2613-2631. [PDF]

  • The N170 is systematically associated with a larger positive potential on the vertex, the vertex positive potential as described by Jeffreys in early studies (1989). In these early studies, the reference electrode was usually a mastoid channel, which emphasized the vertex positive potential and minimized the occipito-temporal negativity that was later termed the N170 by Bentin et al. (1996). Here we compared the N170 under several reference electrode configurations (mastoids, nose, earlobes, non-cephalic, common average) to show that the VPP and N170 are indeed two faces of the same dipolar configuration: one side of the dipole will always be emphasized at the expense of the other one. It is recommended that a common average reference is used to display the N170 component rather than the mastoids (which decrease the component substantially) or the nose (because of artifacts).

Rossion, B., Kung, C.-C., Tarr, M.J. (2004). Visual expertise with nonface objects leads to competition with the early perceptual processing of faces in the human occipitotemporal cortex. PNAS, 101, 14521-14526. [PDF] [slideshow summary]

  • An observer fixates the picture of a Greeble in the center, and the subsequent appearance of a face on the right or left of the Greeble (which remains there) leads to a N170. However, this N170 is largely reduced in amplitude if the observer has been trained with (other) Greebles as compared to the N170 before training, particularly in the right hemisphere. Training does not affect the N170 amplitude when participants fixate a control stimulus. This result suggests that the perceptual encoding of the face suffers from the visual competition created by the fixation of the Greeble stimulus. Irrespective of your interpretation of these findings (and attention is not a valid candidate, see Jacques & Rossion, 2007, Cerebral Cortex), while studies on visual expertise have been criticized for the small and non-replicable effects that they often report, this one truly reports a big effect, in a simple paradigm.

Jacques, C. & Rossion, B. (2004). Concurrent processing reveals competition between visual representations of faces. Neuroreport, 15, 2417-2421. [PDF] [slideshow summary]

  • Subjects fixate a central face that remains on the screen while the N170 to a lateralized face is recorded. We show that the N170 is strongly reduced in this condition, compared to when subjects fixate a phase-scrambled stimulus. This effect reflects a form of competition between faces, which is initiated at the level of the N170. It provides the platform for studies in which subjects fixate objects of expertise while the N170 to a face is recorded (Rossion et al., 2004; 2004).

Goffaux, V., Gauthier, I., Rossion, B. (2003). Spatial scale contribution to early visual differences between face and object processing. Cognitive Brain Research, 16, 416-424. [PDF]

  • We compared the N170 to pictures of faces and cars presented under normal conditions or spatially filtered (low-pass, high-pass). The N170 face effect (larger amplitude to faces than objects) and the latency delay with inversion disappeared for faces presented with only high-spatial frequency (HSF) information. This study suggests that the early encoding of face-specific representations is supported largely by low-spatial frequency (LSF) information. We controlled for the higher contrast provided in the LSF by combining faces with a mask that was filtered in the opposite frequency range (e.g., LSF face with HSF mask). While this procedure offers a better control than when directly comparing HSF and LSF, one limitation of the study is that the LSF mask (high contrast) might have reduced the visibility of the HSF face, increasing the effect.

Rossion, B., Joyce, C.J., Cottrell, G.W., Tarr, M.J. (2003). Early lateralization and orientation tuning for face, word and object processing in the visual cortex. NeuroImage, 20, 1609-1624. [PDF]

  • Nothing special about that study in my opinion, yet it’s one of the papers that gets the most citations ! We replicate the N170 latency delay for inverted faces, and show that it is larger than for other mono-oriented stimuli such as cars and words. One interesting observation is that we compare the lateralization of the N170 to faces and words in the same study, showing a clear right/left dissociation. Source localization of faces vs. objects differences were also reported in this paper, suggesting the primary contribution of a ventral ocicpitotemporal source.

Goffaux, V., Jemel, B., Jacques, C., Rossion, B., Schyns, P.G. (2003). ERP evidence for task modulations on face perceptual processing at different spatial scales. Cognitive Science, 27, 313-325. [PDF]

Rossion, B., Curran, T., Gauthier, I. (2002). A defense of the subordinate-level expertise account for the N170 component. Cognition, 85, 189-196. [PDF]

Rossion, B., Gauthier, I., Goffaux, V., Tarr, M.-J., Crommelinck, M. (2002). Expertise training with novel objects leads to face-like electrophysiological responses. Psychological Science, 13, 250-257. [PDF]

  • This was an ambitious study, in which we wanted to demonstrate that the increase of latency and amplitude of the N170 to faces could be also observed for nonface objects following expertise training. We used Greebles for that. Admittedly, the effect was not as convincing as we wanted: it concerned only the N170 latency increase following inversion, and the effect was somewhat larger on the left than the right hemisphere. A bit disappointing overall, even though further studies have shown similar effects (e.g., Busey & Vanderkolk, 2005).

Rossion, B., Gauthier, I.,Tarr, M.J., Despland, P.-A., Linotte, S., Bruyer, R., Crommelinck, M. (2000). The N170 occipito-temporal component is enhanced and delayed to inverted faces but not to inverted objects: an electrophysiological account of face-specific processes in the human brain, Neuroreport, 11, 1-6. [PDF]

  • The first study to compare the effect of inversion on the N170 to faces and objects. We replicated the increase of amplitude and latency for inverted faces, and showed that this effect did not hold for pictures of familiar objects: chairs, cars, shoes, houses, or a novel object category (greebles). Therefore, the N170 is not only a component that is larger in response to faces than other objects, but it also shows some specific modulations to the same kind of transformation (inversion). A (smaller) latency increase with inversion was found in a next study for pictures of cars though, and for words (Rossion et al., 2003, Neuroimage).

Rossion, B., Campanella, S., Gomez, C., Delinte, A., Debatisse, D., Liard, L., Dubois, S., Bruyer, R., Crommelinck, M., Guérit, J.-M. (1999). Task Modulation of Brain Activity Related to Familiar and Unfamiliar Face Processing: an ERP Study, Clinical Neurophysiology, 110, 449-462. [PDF]

  • One of the first N170 studies that compared the perception of familiar and unfamiliar faces, and failed to find a modulation of the N170 by long-term familiarity of the face.

Rossion, B., Delvenne, J.-F., Debatisse, D., Goffaux, V., Bruyer, R., Crommelinck, M., Guérit, J.-M. (1999). Spatio-temporal brain localization of the face inversion effect, Biological Psychology, 50, 173-189. [PDF]

  • One of the first study (with the short paper of Linkenkaer-Hansen et al., 1998) to report a significant increase of the N170 in response to inverted faces. In our discussion, we raised two possible accounts for this paradoxical increase: (1) that the loss of configural processing following inversion could have resulted in a selective amplification of neural activity devoted to faces because of an increase of difficulty of processing; or (2) that the larger amplitude observed for inverted faces might be a result of the recruitment of additional processing resources in object perception systems. I still believe that these two possibilities probably account for part of the effect, even though other authors have proposed alternative explanations.