Although we commend Lindquist et al. for addressing several ambitious areas of inquiry, including neural activation of discrete emotions, we have several reservations with the authors' empirical assumptions, and with their subsequent conclusions, which leave us with more questions than answers. One concern is that the authors' treatment did not incorporate the numerous drawbacks to inferring psychological processes based on currently available cognitive neurometric technology. Conventional brain imaging devices, for instance, have relatively poor temporal resolution as compared to actual electrical transfer and inter-neuronal communication. The inability to precisely monitor the temporal sequence of localized brain activity combined with the spatial limitations of these techniques severely limits the ability to measure how environmental energy (e.g., task-induced stimuli) is transformed into psychological energy. Moreover, individuals show great variability in anatomical positioning (Amunts et al. Reference Amunts, Weiss, Mohlberg, Pieperhoff, Eickhoff, Gurd, Marshall, Shah, Fink and Zilles2004), and it remains unclear just how and to what extent the types of data that are relied upon to infer brain activation (e.g., relative oxygen blood flow) are representative of, and can be used to map the structure, stages, and feedback of, neural networks.
Another important limitation of the authors' current analyses (and of the broader cognitive neuroscience literature as a whole) is the disproportionate emphasis on measuring brain activation versus brain deactivation. These efforts are based, in part, on the perspective that psychological functioning (both excitatory and inhibitory firing) requires activation processes, and that the absence of neural activity implies the nonexistence of psychological functioning. However, it is well established that certain behaviors, such as lying still with one's eyes closed or passively viewing a visual stimulus – standard baseline control conditions in neuroimaging experiments – are associated with decreased regional brain activity (Raichle et al. Reference Raichle, MacLeod, Snyder, Powers, Gusnard and Shulman2001). Investigations of the visual and auditory cortices have likewise shown reciprocal deactivation when the other region is activated (Laurienti et al. Reference Laurienti, Burdette, Wallace, Yen, Field and Stein2002; Lewis et al. Reference Lewis, Beauchamp and DeYeo2000). Tomasi and colleagues (2006) interpret cross-modal inhibition as intentional deactivation of contra-brain regions, so as to decrease interference from non-relevant neural processes (Tomasi et al. Reference Tomasi, Ernst, Caparelli and Change2006). Lindquist et al. do not consider the concept of intentional deactivation in their analyses, nor do they consider how regions, such as the anterior cingulate cortex (ACC), which make tradeoffs between facilitating either cognitive or emotional processing (only one function is possible at any given time) may have affected their results (Drevets & Raichle Reference Drevets and Raichle1998). Task difficulty, possibly related to differential remote memory retrieval, influences ACC activity (Paus et al. Reference Paus, Koski, Caramanos and Westbury1998), and tasks that require greater cognitive demands may confound analyses intended to measure emotional processing.
In other words, brain deactivation may provide just as important information as activation patterns provide for understanding emotion-processing mechanisms (see also Davidson Reference Davidson1998; Davidson & Irwin Reference Davidson and Irvin1999). Consider the case of amygdala activation, which is a well-established concomitant of threat processing and subsequent elicitation of fear and disgust responses, as the authors show. What the authors fail to address, however, is the importance of amygdala deactivation, which the authors also show is indicative of experiencing anger and joy. This makes sense, as both anger and joy are demonstrative of empowerment, and therefore systematically occur in response to the appraisal of non-threatening stimuli (Vigil Reference Vigil2009). Lesion and neuroimaging studies show that amygdala activation is necessary for detecting distrust, and when the amygdala is deactivated or impaired, individuals are more likely to infer trustworthiness and benign attributes in others (e.g., Adolphs et al. Reference Adolphs, Tranel and Damasio1998; Engell et al. Reference Engell, Haxby and Todorov2007; Winston et al. Reference Winston, Strange, O'Doherty and Dolan2002; Zald Reference Zald2003). It is therefore likely that the inhibition or absence of amygdala activity may facilitate specialized and functional elements of social cognition, particularly in social situations that favor cooperative over avoidant behavioral strategies.
Unfortunately, we are uninspired by the utility of the authors' currently described “conceptual act model” of discrete emotionality, which can arguably be interpreted as another form of “locationist” model, substituting broader psychological constructs (e.g., memories, knowledge) for the more specific constructs (e.g., natural kinds) that the authors argue against. Moreover, the authors' core hypothesis that “people make meaning” out of physiological states, subsequently resulting in emotional experiences, is indistinguishable from an embodied-simulation model of emotional processing (e.g., see Niedenthal et al. Reference Niedenthal, Mermillod, Maringer and Hess2010), which we have argued against elsewhere (Vigil & Coulombe Reference Vigil and Coulombe2010). In particular, we showed that the mere evaluations of core trait impressions of trustworthiness and capacity are both necessary and sufficient for predicting interpersonal dispositions (e.g., to affiliate or avoid; see e.g., Cacioppo et al. Reference Cacioppo, Gardner and Berntson1999; Gray Reference Gray, Ekman and Davidson1994; Lang et al. Reference Lang, Bradley and Cuthbert1990) and discrete emotional reactions (e.g., felt disgust vs. sympathy) towards others (see also, e.g., Fiske et al. Reference Fiske, Cuddy and Glick2006; Rosenberg et al. Reference Rosenberg, Nelson and Vivekananthan1968; Todorov Reference Todorov2008; Vigil Reference Vigil2009; Wojciszke Reference Wojciszke2005). Therefore, the recourse to prior experience and personal meaning of a given context may not always be necessary for explaining how and why emotional and broader affective-behavioral processing occurs.
Lindquist et al. have built their argument such that if criteria for the locationist argument are not met, it is assumed to be support for the psychological constructionist perspective. This is misleading, and fails to recognize other possible explanations. One alternative explanation, of many, is H. C. Barrett's (Reference Barrett2005) analogy that cognitive modules use a template matching system similar to that used by enzymes. In modular models of human cognition it is not necessary that brain activity be localized to specific areas across participants due to factors such as plasticity and the brain's reorganizational capabilities in response to injury (e.g., H. C. Barrett Reference Barrett2005; H. C. Barrett & Kurzban Reference Barrett and Kurzban2006; Marshall Reference Marshall1984; Robertson & Murre Reference Robertson and Murre1999). Modularity is a central concept of the computational model of the mind, and although there is disagreement as to the extent to which the mind is modular, there is broad agreement that it is at least somewhat modularized (e.g., Barrett & Kurzban Reference Barrett and Kurzban2006; Hagen Reference Hagen and Buss2005). Future research that can incorporate multi-dimensional techniques, such as activation-based techniques (e.g., neuroimaging) and disruption-based techniques (e.g., temporary lesion methods), will eventually elucidate the form and function of discrete emotionality, as well as guide the development of clinical applications for cognitive neuroscentific research (e.g., Pouratian et al. Reference Pouratian, Sheth, Martine and Toga2003; Rorden & Karnath Reference Rorden and Karnath2004).
Although we commend Lindquist et al. for addressing several ambitious areas of inquiry, including neural activation of discrete emotions, we have several reservations with the authors' empirical assumptions, and with their subsequent conclusions, which leave us with more questions than answers. One concern is that the authors' treatment did not incorporate the numerous drawbacks to inferring psychological processes based on currently available cognitive neurometric technology. Conventional brain imaging devices, for instance, have relatively poor temporal resolution as compared to actual electrical transfer and inter-neuronal communication. The inability to precisely monitor the temporal sequence of localized brain activity combined with the spatial limitations of these techniques severely limits the ability to measure how environmental energy (e.g., task-induced stimuli) is transformed into psychological energy. Moreover, individuals show great variability in anatomical positioning (Amunts et al. Reference Amunts, Weiss, Mohlberg, Pieperhoff, Eickhoff, Gurd, Marshall, Shah, Fink and Zilles2004), and it remains unclear just how and to what extent the types of data that are relied upon to infer brain activation (e.g., relative oxygen blood flow) are representative of, and can be used to map the structure, stages, and feedback of, neural networks.
Another important limitation of the authors' current analyses (and of the broader cognitive neuroscience literature as a whole) is the disproportionate emphasis on measuring brain activation versus brain deactivation. These efforts are based, in part, on the perspective that psychological functioning (both excitatory and inhibitory firing) requires activation processes, and that the absence of neural activity implies the nonexistence of psychological functioning. However, it is well established that certain behaviors, such as lying still with one's eyes closed or passively viewing a visual stimulus – standard baseline control conditions in neuroimaging experiments – are associated with decreased regional brain activity (Raichle et al. Reference Raichle, MacLeod, Snyder, Powers, Gusnard and Shulman2001). Investigations of the visual and auditory cortices have likewise shown reciprocal deactivation when the other region is activated (Laurienti et al. Reference Laurienti, Burdette, Wallace, Yen, Field and Stein2002; Lewis et al. Reference Lewis, Beauchamp and DeYeo2000). Tomasi and colleagues (2006) interpret cross-modal inhibition as intentional deactivation of contra-brain regions, so as to decrease interference from non-relevant neural processes (Tomasi et al. Reference Tomasi, Ernst, Caparelli and Change2006). Lindquist et al. do not consider the concept of intentional deactivation in their analyses, nor do they consider how regions, such as the anterior cingulate cortex (ACC), which make tradeoffs between facilitating either cognitive or emotional processing (only one function is possible at any given time) may have affected their results (Drevets & Raichle Reference Drevets and Raichle1998). Task difficulty, possibly related to differential remote memory retrieval, influences ACC activity (Paus et al. Reference Paus, Koski, Caramanos and Westbury1998), and tasks that require greater cognitive demands may confound analyses intended to measure emotional processing.
In other words, brain deactivation may provide just as important information as activation patterns provide for understanding emotion-processing mechanisms (see also Davidson Reference Davidson1998; Davidson & Irwin Reference Davidson and Irvin1999). Consider the case of amygdala activation, which is a well-established concomitant of threat processing and subsequent elicitation of fear and disgust responses, as the authors show. What the authors fail to address, however, is the importance of amygdala deactivation, which the authors also show is indicative of experiencing anger and joy. This makes sense, as both anger and joy are demonstrative of empowerment, and therefore systematically occur in response to the appraisal of non-threatening stimuli (Vigil Reference Vigil2009). Lesion and neuroimaging studies show that amygdala activation is necessary for detecting distrust, and when the amygdala is deactivated or impaired, individuals are more likely to infer trustworthiness and benign attributes in others (e.g., Adolphs et al. Reference Adolphs, Tranel and Damasio1998; Engell et al. Reference Engell, Haxby and Todorov2007; Winston et al. Reference Winston, Strange, O'Doherty and Dolan2002; Zald Reference Zald2003). It is therefore likely that the inhibition or absence of amygdala activity may facilitate specialized and functional elements of social cognition, particularly in social situations that favor cooperative over avoidant behavioral strategies.
Unfortunately, we are uninspired by the utility of the authors' currently described “conceptual act model” of discrete emotionality, which can arguably be interpreted as another form of “locationist” model, substituting broader psychological constructs (e.g., memories, knowledge) for the more specific constructs (e.g., natural kinds) that the authors argue against. Moreover, the authors' core hypothesis that “people make meaning” out of physiological states, subsequently resulting in emotional experiences, is indistinguishable from an embodied-simulation model of emotional processing (e.g., see Niedenthal et al. Reference Niedenthal, Mermillod, Maringer and Hess2010), which we have argued against elsewhere (Vigil & Coulombe Reference Vigil and Coulombe2010). In particular, we showed that the mere evaluations of core trait impressions of trustworthiness and capacity are both necessary and sufficient for predicting interpersonal dispositions (e.g., to affiliate or avoid; see e.g., Cacioppo et al. Reference Cacioppo, Gardner and Berntson1999; Gray Reference Gray, Ekman and Davidson1994; Lang et al. Reference Lang, Bradley and Cuthbert1990) and discrete emotional reactions (e.g., felt disgust vs. sympathy) towards others (see also, e.g., Fiske et al. Reference Fiske, Cuddy and Glick2006; Rosenberg et al. Reference Rosenberg, Nelson and Vivekananthan1968; Todorov Reference Todorov2008; Vigil Reference Vigil2009; Wojciszke Reference Wojciszke2005). Therefore, the recourse to prior experience and personal meaning of a given context may not always be necessary for explaining how and why emotional and broader affective-behavioral processing occurs.
Lindquist et al. have built their argument such that if criteria for the locationist argument are not met, it is assumed to be support for the psychological constructionist perspective. This is misleading, and fails to recognize other possible explanations. One alternative explanation, of many, is H. C. Barrett's (Reference Barrett2005) analogy that cognitive modules use a template matching system similar to that used by enzymes. In modular models of human cognition it is not necessary that brain activity be localized to specific areas across participants due to factors such as plasticity and the brain's reorganizational capabilities in response to injury (e.g., H. C. Barrett Reference Barrett2005; H. C. Barrett & Kurzban Reference Barrett and Kurzban2006; Marshall Reference Marshall1984; Robertson & Murre Reference Robertson and Murre1999). Modularity is a central concept of the computational model of the mind, and although there is disagreement as to the extent to which the mind is modular, there is broad agreement that it is at least somewhat modularized (e.g., Barrett & Kurzban Reference Barrett and Kurzban2006; Hagen Reference Hagen and Buss2005). Future research that can incorporate multi-dimensional techniques, such as activation-based techniques (e.g., neuroimaging) and disruption-based techniques (e.g., temporary lesion methods), will eventually elucidate the form and function of discrete emotionality, as well as guide the development of clinical applications for cognitive neuroscentific research (e.g., Pouratian et al. Reference Pouratian, Sheth, Martine and Toga2003; Rorden & Karnath Reference Rorden and Karnath2004).