Firestone & Scholl (F&S) argue against top-down influences of higher-level social cognitive factors (e.g., beliefs, desires, and emotion) on perception. They stipulate the conditions in which genuine top-down effects could be established and highlight a handful of pitfalls – some previous demonstrations of top-down effects in which the conditions were not satisfied.
For example, F&S criticize a previous finding that positive (vs. negative) thoughts made the world look brighter (vs. darker, Meier et al. Reference Meier, Robinson, Crawford and Ahlvers2007). They rule out the possibility that these findings were results of cognitive penetration on perception. Specifically, in a task (Fig. 1A) modeled after Study 4 in Meier et al. (Reference Meier, Robinson, Crawford and Ahlvers2007), participants discriminate between a darker and a brighter luminance probe following activation of emotional concepts using words with positive or negative meanings. If perception is modulated by emotional concepts, perceptual representations of the brighter probe and the darker probe should both shift rightward by positive concepts, resulting in indistinguishable luminance discriminability (i.e., d′ in Signal Detection Theory, SDT) between the two luminance probes across emotion conditions (dashed lines in Fig. 1B). F&S thus argue that a genuine shift of perception by top-down factors could not manifest in behavioral reports (the El Greco fallacy, Pitfall 1). Therefore, any behavioral manifestation of changes in brightness perception induced by emotional concepts should result from response biases originating from postperceptual judgments (Firestone & Scholl Reference Firestone and Scholl2014b) or low-level stimulus differences originating from bottom-up features (Firestone & Scholl Reference Firestone and Scholl2015a; Lu et al. Reference Lu, Guo, Boguslavsky, Cappiello, Zhang and Meng2015).
While they have clearly demonstrated conceptual problems with the El Greco fallacy, F&S did not propose a solution for it. In the example of perceived brightness, a potential solution for this fallacy is to use direct or indirect assessment of perceived brightness, such as pupillometry, instead of relying on behavioral performance. Pupillary light response is traditionally believed to purely rely on bottom-up factors. However, some recent research has revealed robust cognitive effects on pupillary light responses (Hartmann & Fischer Reference Hartmann and Fischer2014; Laeng et al. Reference Laeng, Sirois and Gredebäck2012). That is, pupil size can be modulated by perceived brightness independent of physical brightness (e.g., Laeng & Endestad Reference Laeng and Endestad2012; Laeng & Sulutvedt Reference Laeng and Sulutvedt2014; Mathôt et al. Reference Mathôt, van der Linden, Grainger and Vitu2015; Naber & Nakayama Reference Naber and Nakayama2013). For example, thinking about a bright event (e.g., a sunny day) leads to pupil constriction (Laeng & Sulutvedt Reference Laeng and Sulutvedt2014). These pupillary effects have been taken as evidence for cognitive penetrability (Hartmann & Fischer Reference Hartmann and Fischer2014), in that they are similar to pupillary responses to “real” visual perception induced by low-level physical stimuli.
Xie & Zhang (Reference Xie and Zhangin preparation) generalized these pupillary effects in an experiment (Fig. 1A) modified from Study 4 in Meier et al. (Reference Meier, Robinson, Crawford and Ahlvers2007). Accuracy in this experiment replicated the previous finding (Meier et al. Reference Meier, Robinson, Crawford and Ahlvers2007) that participants were more accurate in making a “brighter” response in the positive condition than in a negative condition. However, perceptual discriminability of the two luminance probes (d′, indicated by the dotted lines in Fig. 1B) was comparable between positive and negative conditions, as suggested by the El Greco fallacy, and participants were more inclined (more liberal response) to report brighter perception following positive thoughts than negative thoughts. These SDT measures alone seemed to suggest that effects of affective concepts on brightness perception were largely driven by response biases. However, these results were also consistent with a genuine shift in perceived brightness, as shown in Figure 1B, with a constant response criterion across the two conditions. Of these two possibilities, only the latter was supported by the pupil size data in that positive thoughts induced smaller pupil constriction for both luminance probes (arrows with solid lines in Fig. 1B), consequently resulting in larger pupil size for brighter perception (Chung & Pease Reference Chung and Pease1999), than did negative thoughts. Note, the pupil effect here cannot be attributed to contextual priming or sensory adaptations. Together, these results supported, and more important provided a plausible mechanism for, the effects of emotional concepts on perceived brightness.
The pupil effect here refers to phasic changes in pupillary light response to the luminance probe, reflecting the transient sensory processing underlying the resulting perceived brightness. This phasic pupil size effect is different from tonic changes in pupil size elicited by affective concepts in Xie & Zhang (Reference Xie and Zhangin preparation), in that tonic changes may result from processes that are not evoked by probe perception, such as arousal, task demand, and decisional uncertainty (Murphy et al. Reference Murphy, Vandekerckhove and Nieuwenhuis2014). The tonic pupil size effects are therefore similar to differences in eye shapes (and thus pupil size) as intrinsic features of facial expressions in a previous study (Lee et al. Reference Lee, Mirza, Flanagan and Anderson2014). F&S regard these tonic effects as changes in states of sensory organ (e.g., open vs. closed eye), and consequently F&S do not consider their effects on perception as evidence for cognitive penetrability. However, the phasic pupil size effects elicited by luminance probes are by no means changes in states of sensory organ, and therefore they warrant full consideration as candidates for evidence supporting cognitive penetrability.
Similar arguments can be made for perceptual effects of attention, which F&S simply attributed to changes in sensory inputs, instead of changes in sensory processing. This perspective seems to be an oversimplification. First, research on endogenous attention typically manipulates attention independent of eye movements (e.g., by presenting stimulus at fixation). The physical stimuli are thus kept constant between conditions, leading to the exact same optical inputs for sensory processing. Second, attention transiently modulates early feedforward sensory processing by amplifying sensory gain of attended information (Hillyard et al. Reference Hillyard, Vogel and Luck1998; Zhang & Luck Reference Zhang and Luck2009). It is therefore shortsighted to disregard perceptual effects of attention for cognitive penetrability.
In this commentary, we briefly reviewed some recent pupillary evidence supporting top-down modulation of perception and the justification for including attentional effects in tests of cognitive penetrability. Together, these pieces of evidence suggest that cognition can affect perception.
Firestone & Scholl (F&S) argue against top-down influences of higher-level social cognitive factors (e.g., beliefs, desires, and emotion) on perception. They stipulate the conditions in which genuine top-down effects could be established and highlight a handful of pitfalls – some previous demonstrations of top-down effects in which the conditions were not satisfied.
For example, F&S criticize a previous finding that positive (vs. negative) thoughts made the world look brighter (vs. darker, Meier et al. Reference Meier, Robinson, Crawford and Ahlvers2007). They rule out the possibility that these findings were results of cognitive penetration on perception. Specifically, in a task (Fig. 1A) modeled after Study 4 in Meier et al. (Reference Meier, Robinson, Crawford and Ahlvers2007), participants discriminate between a darker and a brighter luminance probe following activation of emotional concepts using words with positive or negative meanings. If perception is modulated by emotional concepts, perceptual representations of the brighter probe and the darker probe should both shift rightward by positive concepts, resulting in indistinguishable luminance discriminability (i.e., d′ in Signal Detection Theory, SDT) between the two luminance probes across emotion conditions (dashed lines in Fig. 1B). F&S thus argue that a genuine shift of perception by top-down factors could not manifest in behavioral reports (the El Greco fallacy, Pitfall 1). Therefore, any behavioral manifestation of changes in brightness perception induced by emotional concepts should result from response biases originating from postperceptual judgments (Firestone & Scholl Reference Firestone and Scholl2014b) or low-level stimulus differences originating from bottom-up features (Firestone & Scholl Reference Firestone and Scholl2015a; Lu et al. Reference Lu, Guo, Boguslavsky, Cappiello, Zhang and Meng2015).
Figure 1 Illustration of the task (A) and findings (B) from Xie & Zhang (Reference Xie and Zhangin preparation).
While they have clearly demonstrated conceptual problems with the El Greco fallacy, F&S did not propose a solution for it. In the example of perceived brightness, a potential solution for this fallacy is to use direct or indirect assessment of perceived brightness, such as pupillometry, instead of relying on behavioral performance. Pupillary light response is traditionally believed to purely rely on bottom-up factors. However, some recent research has revealed robust cognitive effects on pupillary light responses (Hartmann & Fischer Reference Hartmann and Fischer2014; Laeng et al. Reference Laeng, Sirois and Gredebäck2012). That is, pupil size can be modulated by perceived brightness independent of physical brightness (e.g., Laeng & Endestad Reference Laeng and Endestad2012; Laeng & Sulutvedt Reference Laeng and Sulutvedt2014; Mathôt et al. Reference Mathôt, van der Linden, Grainger and Vitu2015; Naber & Nakayama Reference Naber and Nakayama2013). For example, thinking about a bright event (e.g., a sunny day) leads to pupil constriction (Laeng & Sulutvedt Reference Laeng and Sulutvedt2014). These pupillary effects have been taken as evidence for cognitive penetrability (Hartmann & Fischer Reference Hartmann and Fischer2014), in that they are similar to pupillary responses to “real” visual perception induced by low-level physical stimuli.
Xie & Zhang (Reference Xie and Zhangin preparation) generalized these pupillary effects in an experiment (Fig. 1A) modified from Study 4 in Meier et al. (Reference Meier, Robinson, Crawford and Ahlvers2007). Accuracy in this experiment replicated the previous finding (Meier et al. Reference Meier, Robinson, Crawford and Ahlvers2007) that participants were more accurate in making a “brighter” response in the positive condition than in a negative condition. However, perceptual discriminability of the two luminance probes (d′, indicated by the dotted lines in Fig. 1B) was comparable between positive and negative conditions, as suggested by the El Greco fallacy, and participants were more inclined (more liberal response) to report brighter perception following positive thoughts than negative thoughts. These SDT measures alone seemed to suggest that effects of affective concepts on brightness perception were largely driven by response biases. However, these results were also consistent with a genuine shift in perceived brightness, as shown in Figure 1B, with a constant response criterion across the two conditions. Of these two possibilities, only the latter was supported by the pupil size data in that positive thoughts induced smaller pupil constriction for both luminance probes (arrows with solid lines in Fig. 1B), consequently resulting in larger pupil size for brighter perception (Chung & Pease Reference Chung and Pease1999), than did negative thoughts. Note, the pupil effect here cannot be attributed to contextual priming or sensory adaptations. Together, these results supported, and more important provided a plausible mechanism for, the effects of emotional concepts on perceived brightness.
The pupil effect here refers to phasic changes in pupillary light response to the luminance probe, reflecting the transient sensory processing underlying the resulting perceived brightness. This phasic pupil size effect is different from tonic changes in pupil size elicited by affective concepts in Xie & Zhang (Reference Xie and Zhangin preparation), in that tonic changes may result from processes that are not evoked by probe perception, such as arousal, task demand, and decisional uncertainty (Murphy et al. Reference Murphy, Vandekerckhove and Nieuwenhuis2014). The tonic pupil size effects are therefore similar to differences in eye shapes (and thus pupil size) as intrinsic features of facial expressions in a previous study (Lee et al. Reference Lee, Mirza, Flanagan and Anderson2014). F&S regard these tonic effects as changes in states of sensory organ (e.g., open vs. closed eye), and consequently F&S do not consider their effects on perception as evidence for cognitive penetrability. However, the phasic pupil size effects elicited by luminance probes are by no means changes in states of sensory organ, and therefore they warrant full consideration as candidates for evidence supporting cognitive penetrability.
Similar arguments can be made for perceptual effects of attention, which F&S simply attributed to changes in sensory inputs, instead of changes in sensory processing. This perspective seems to be an oversimplification. First, research on endogenous attention typically manipulates attention independent of eye movements (e.g., by presenting stimulus at fixation). The physical stimuli are thus kept constant between conditions, leading to the exact same optical inputs for sensory processing. Second, attention transiently modulates early feedforward sensory processing by amplifying sensory gain of attended information (Hillyard et al. Reference Hillyard, Vogel and Luck1998; Zhang & Luck Reference Zhang and Luck2009). It is therefore shortsighted to disregard perceptual effects of attention for cognitive penetrability.
In this commentary, we briefly reviewed some recent pupillary evidence supporting top-down modulation of perception and the justification for including attentional effects in tests of cognitive penetrability. Together, these pieces of evidence suggest that cognition can affect perception.