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Swimming with dolphins
234
News & Comment
had moved and to report this by glancing left or right. Like humans performing the same task, the money fell foul of the ‘displacement illusion’ if the frame moved more than the spot. For example, if the spot were to shift 1 degree to the left but the frame shifts 2 degrees left, subjects respond ‘right’. However, they can still make accurate leftward eye movements to the new location – suggesting that the system for shifting fixation to the displaced target is separate from the system for perceiving and reporting its displacement. Recording in prefrontal cortex, the researchers found a population of ‘report-related’ cells that reflected the monkey’s report of the displacement (even when wrong). A different population of directionallyselective cells was active when the monkey was simply required to glance at the target
TRENDS in Cognitive Sciences Vol.5 No.6 June 2001
in its new location. This is the first study to demonstrate illusion-related activity in prefrontal cortex and to contrast it with movement-related activity. HJB
Swimming with dolphins Recognizing oneself in a mirror is something that only humans and great apes were thought to be able to do – until now that is. A recent report from Diana Reiss and Lori Marino in New York suggests that dolphins might also be capable of self-recognition [Proc. Natl. Acad. Sci. U. S. A. (2001) 98, 5937–5942]. The standard ‘mirror test’, in which animals respond to marks added by the experimenter to areas of their body that can only be seen in a reflection, was adapted for the dolphin study, and the
researchers found evidence that two bottlenose dolphins made mark-directed responses ; that is, they were aware that it was their own body in the reflection, not that of another dolphin. The significance of passing the mirror test is that selfrecognition is an indicator of selfawareness, and that is a form of consciousness found only in animals that have complex social behaviours requiring the ability to model one’s own, and other individuals’ cognitive states. It seems that the dolphins are swimming with us in more ways than one. JO In Brief articles written by Heidi Johansen-Berg Mark Wexler and Julian Ogilvie
Letters
A two-way window on face recognition Ellis and Lewis1 recently reviewed the Breen et al. two-route model of face recognition2 and agreed that, unlike previous single-route accounts of face processing, the Breen et al. model parsimoniously accounted for the double dissociation between reduced autonomic responses to recognized familiar faces in patients with Capgras delusion3,4, and preserved autonomic responses to familiar faces that are not overtly recognized in patients with prosopagnosia5–7. As shown in Fig. 1, Breen et al. proposed that, following early structural encoding and processing at the level of the Face Recognition Units (FRU), the model then bifurcates with one pathway leading directly from the FRU to the Person Identity Nodes (PIN) and a second pathway leading to an affective response. Breen et al. suggest that a disruption at the level of the FRUs, or a disconnection between the FRUs and the PINs, could result in impaired overt face recognition but intact autonomic responses to familiar faces (as seen in prosopagnosia), whereas a disruption either in the connection between the FRUs and the affective response to familiar stimuli, or in the affective response to familiar stimuli
Structural encoding
Expression analysis
Speech
Visual processing
FRU
PIN
Name retrieval
Arousal, orienting response Affective response to familiar stimuli
SCR
TRENDS in Cognitive Sciences
Fig. 1. Model of face processing proposed by Breen et al.2 It proposes two independent pathways from the Face Recognition Units (FRU), one leading to the Person Identity Nodes (PIN), and from there to name retrieval, and the second leading to the affective response to familiar stimuli, which can be measured by the Skin Conductance Response (SCR). The SCR is also a measure of the arousal or orienting response, located in a separate module. Note that there is two-way flow of information between the PIN and affective response modules, which reinforces their activation for a given face.
itself, could lead to intact overt face recognition but a reduced or absent autonomic response to familiar faces (as demonstrated in Capgras patients). Ellis and Lewis proposed that the Breen et al. model lacked a facility needed to re-integrate, and compare, the outputs
of the two routes to face recognition with the stored (and therefore expected) representations. Specifically, they proposed that the model needed to include an ‘Integrative Device’ that would compare the expected response to the actual response in relation to both
http://tics.trends.com 1364-6613/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII: S1364-6613(00)01659-4
News & Comment
had moved and to report this by glancing left or right. Like humans performing the same task, the money fell foul of the ‘displacement illusion’ if the frame moved more than the spot. For example, if the spot were to shift 1 degree to the left but the frame shifts 2 degrees left, subjects respond ‘right’. However, they can still make accurate leftward eye movements to the new location – suggesting that the system for shifting fixation to the displaced target is separate from the system for perceiving and reporting its displacement. Recording in prefrontal cortex, the researchers found a population of ‘report-related’ cells that reflected the monkey’s report of the displacement (even when wrong). A different population of directionallyselective cells was active when the monkey was simply required to glance at the target
TRENDS in Cognitive Sciences Vol.5 No.6 June 2001
in its new location. This is the first study to demonstrate illusion-related activity in prefrontal cortex and to contrast it with movement-related activity. HJB
Swimming with dolphins Recognizing oneself in a mirror is something that only humans and great apes were thought to be able to do – until now that is. A recent report from Diana Reiss and Lori Marino in New York suggests that dolphins might also be capable of self-recognition [Proc. Natl. Acad. Sci. U. S. A. (2001) 98, 5937–5942]. The standard ‘mirror test’, in which animals respond to marks added by the experimenter to areas of their body that can only be seen in a reflection, was adapted for the dolphin study, and the
researchers found evidence that two bottlenose dolphins made mark-directed responses ; that is, they were aware that it was their own body in the reflection, not that of another dolphin. The significance of passing the mirror test is that selfrecognition is an indicator of selfawareness, and that is a form of consciousness found only in animals that have complex social behaviours requiring the ability to model one’s own, and other individuals’ cognitive states. It seems that the dolphins are swimming with us in more ways than one. JO In Brief articles written by Heidi Johansen-Berg Mark Wexler and Julian Ogilvie
Letters
A two-way window on face recognition Ellis and Lewis1 recently reviewed the Breen et al. two-route model of face recognition2 and agreed that, unlike previous single-route accounts of face processing, the Breen et al. model parsimoniously accounted for the double dissociation between reduced autonomic responses to recognized familiar faces in patients with Capgras delusion3,4, and preserved autonomic responses to familiar faces that are not overtly recognized in patients with prosopagnosia5–7. As shown in Fig. 1, Breen et al. proposed that, following early structural encoding and processing at the level of the Face Recognition Units (FRU), the model then bifurcates with one pathway leading directly from the FRU to the Person Identity Nodes (PIN) and a second pathway leading to an affective response. Breen et al. suggest that a disruption at the level of the FRUs, or a disconnection between the FRUs and the PINs, could result in impaired overt face recognition but intact autonomic responses to familiar faces (as seen in prosopagnosia), whereas a disruption either in the connection between the FRUs and the affective response to familiar stimuli, or in the affective response to familiar stimuli
Structural encoding
Expression analysis
Speech
Visual processing
FRU
PIN
Name retrieval
Arousal, orienting response Affective response to familiar stimuli
SCR
TRENDS in Cognitive Sciences
Fig. 1. Model of face processing proposed by Breen et al.2 It proposes two independent pathways from the Face Recognition Units (FRU), one leading to the Person Identity Nodes (PIN), and from there to name retrieval, and the second leading to the affective response to familiar stimuli, which can be measured by the Skin Conductance Response (SCR). The SCR is also a measure of the arousal or orienting response, located in a separate module. Note that there is two-way flow of information between the PIN and affective response modules, which reinforces their activation for a given face.
itself, could lead to intact overt face recognition but a reduced or absent autonomic response to familiar faces (as demonstrated in Capgras patients). Ellis and Lewis proposed that the Breen et al. model lacked a facility needed to re-integrate, and compare, the outputs
of the two routes to face recognition with the stored (and therefore expected) representations. Specifically, they proposed that the model needed to include an ‘Integrative Device’ that would compare the expected response to the actual response in relation to both
http://tics.trends.com 1364-6613/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII: S1364-6613(00)01659-4