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Human olfaction: a constant state of change-blindness.

Sela L, Sobel N - Exp Brain Res (2010)

Bottom Line: Regarding the temporal envelope, whereas vision and audition consist of nearly continuous input, olfactory input is discreet, made of sniffs widely separated in time.Therefore, attentional capture in olfaction is minimal, as is human olfactory awareness.All this, however, does not diminish the role of olfaction through sub-attentive mechanisms allowing subliminal smells a profound influence on human behavior and perception.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, The Weizmann Institute of Science, Rehovot, 76100, Israel.

ABSTRACT
Paradoxically, although humans have a superb sense of smell, they don't trust their nose. Furthermore, although human odorant detection thresholds are very low, only unusually high odorant concentrations spontaneously shift our attention to olfaction. Here we suggest that this lack of olfactory awareness reflects the nature of olfactory attention that is shaped by the spatial and temporal envelopes of olfaction. Regarding the spatial envelope, selective attention is allocated in space. Humans direct an attentional spotlight within spatial coordinates in both vision and audition. Human olfactory spatial abilities are minimal. Thus, with no olfactory space, there is no arena for olfactory selective attention. Regarding the temporal envelope, whereas vision and audition consist of nearly continuous input, olfactory input is discreet, made of sniffs widely separated in time. If similar temporal breaks are artificially introduced to vision and audition, they induce "change blindness", a loss of attentional capture that results in a lack of awareness to change. Whereas "change blindness" is an aberration of vision and audition, the long inter-sniff-interval renders "change anosmia" the norm in human olfaction. Therefore, attentional capture in olfaction is minimal, as is human olfactory awareness. All this, however, does not diminish the role of olfaction through sub-attentive mechanisms allowing subliminal smells a profound influence on human behavior and perception.

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The influence of subliminal odors a Results from Li et al. (2007). Increased odor awareness (x axis) was associated with a reduced influence on judgments (y axis). b Results from Epple and Herz (1999). Mean performance on a cognitive test by 5-year old children as a function of odor condition. Participants in the “same odor” condition (an odor previously associated with a frustrating task) performed worse than participants in the “different odor” or “no odor” groups (P < 0.05). c Results from Holland et al. (2005). Mean reaction times for cleaning related words and control words in odor and control conditions (without an odor) during a lexical decision task. Participants responded faster to cleaning-related words than to control words (P < 0.05), and excluding participants that have been aware of the odor, revealed a significant interaction between odor presence and word type (P < 0.05)
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Fig6: The influence of subliminal odors a Results from Li et al. (2007). Increased odor awareness (x axis) was associated with a reduced influence on judgments (y axis). b Results from Epple and Herz (1999). Mean performance on a cognitive test by 5-year old children as a function of odor condition. Participants in the “same odor” condition (an odor previously associated with a frustrating task) performed worse than participants in the “different odor” or “no odor” groups (P < 0.05). c Results from Holland et al. (2005). Mean reaction times for cleaning related words and control words in odor and control conditions (without an odor) during a lexical decision task. Participants responded faster to cleaning-related words than to control words (P < 0.05), and excluding participants that have been aware of the odor, revealed a significant interaction between odor presence and word type (P < 0.05)

Mentions: In a more recent study that was closer to Type A than Type B, the appeal of human faces was estimated in the presence of one of three different odorants; the pleasant citral, the neutral anisole, and the unpleasant valeric acid (Li et al. 2007). The odorants were presented at very low concentrations. The subjects tried to smell the odorants (hence Type A), and then conducted the task. The hedonic value of the odorants altered the appeal of the faces, but only for those subjects who were unable to detect the odorants (Fig. 6a). In other words, consistent with the previously reported increased brain activity associated with the unattend over the attend condition (Sabri et al. 2005), when odorants were not consciously perceived they had a greater effect on perception. The initial results obtained by Cowely et al. combined with numerous Type A studies (Cowley and Brooksbank 1991; Cutler et al. 1998; McCoy and Pitino 2002; Saxton et al. 2008), to suggest that subliminal odors can influence social judgments.Fig. 6


Human olfaction: a constant state of change-blindness.

Sela L, Sobel N - Exp Brain Res (2010)

The influence of subliminal odors a Results from Li et al. (2007). Increased odor awareness (x axis) was associated with a reduced influence on judgments (y axis). b Results from Epple and Herz (1999). Mean performance on a cognitive test by 5-year old children as a function of odor condition. Participants in the “same odor” condition (an odor previously associated with a frustrating task) performed worse than participants in the “different odor” or “no odor” groups (P < 0.05). c Results from Holland et al. (2005). Mean reaction times for cleaning related words and control words in odor and control conditions (without an odor) during a lexical decision task. Participants responded faster to cleaning-related words than to control words (P < 0.05), and excluding participants that have been aware of the odor, revealed a significant interaction between odor presence and word type (P < 0.05)
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2908748&req=5

Fig6: The influence of subliminal odors a Results from Li et al. (2007). Increased odor awareness (x axis) was associated with a reduced influence on judgments (y axis). b Results from Epple and Herz (1999). Mean performance on a cognitive test by 5-year old children as a function of odor condition. Participants in the “same odor” condition (an odor previously associated with a frustrating task) performed worse than participants in the “different odor” or “no odor” groups (P < 0.05). c Results from Holland et al. (2005). Mean reaction times for cleaning related words and control words in odor and control conditions (without an odor) during a lexical decision task. Participants responded faster to cleaning-related words than to control words (P < 0.05), and excluding participants that have been aware of the odor, revealed a significant interaction between odor presence and word type (P < 0.05)
Mentions: In a more recent study that was closer to Type A than Type B, the appeal of human faces was estimated in the presence of one of three different odorants; the pleasant citral, the neutral anisole, and the unpleasant valeric acid (Li et al. 2007). The odorants were presented at very low concentrations. The subjects tried to smell the odorants (hence Type A), and then conducted the task. The hedonic value of the odorants altered the appeal of the faces, but only for those subjects who were unable to detect the odorants (Fig. 6a). In other words, consistent with the previously reported increased brain activity associated with the unattend over the attend condition (Sabri et al. 2005), when odorants were not consciously perceived they had a greater effect on perception. The initial results obtained by Cowely et al. combined with numerous Type A studies (Cowley and Brooksbank 1991; Cutler et al. 1998; McCoy and Pitino 2002; Saxton et al. 2008), to suggest that subliminal odors can influence social judgments.Fig. 6

Bottom Line: Regarding the temporal envelope, whereas vision and audition consist of nearly continuous input, olfactory input is discreet, made of sniffs widely separated in time.Therefore, attentional capture in olfaction is minimal, as is human olfactory awareness.All this, however, does not diminish the role of olfaction through sub-attentive mechanisms allowing subliminal smells a profound influence on human behavior and perception.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, The Weizmann Institute of Science, Rehovot, 76100, Israel.

ABSTRACT
Paradoxically, although humans have a superb sense of smell, they don't trust their nose. Furthermore, although human odorant detection thresholds are very low, only unusually high odorant concentrations spontaneously shift our attention to olfaction. Here we suggest that this lack of olfactory awareness reflects the nature of olfactory attention that is shaped by the spatial and temporal envelopes of olfaction. Regarding the spatial envelope, selective attention is allocated in space. Humans direct an attentional spotlight within spatial coordinates in both vision and audition. Human olfactory spatial abilities are minimal. Thus, with no olfactory space, there is no arena for olfactory selective attention. Regarding the temporal envelope, whereas vision and audition consist of nearly continuous input, olfactory input is discreet, made of sniffs widely separated in time. If similar temporal breaks are artificially introduced to vision and audition, they induce "change blindness", a loss of attentional capture that results in a lack of awareness to change. Whereas "change blindness" is an aberration of vision and audition, the long inter-sniff-interval renders "change anosmia" the norm in human olfaction. Therefore, attentional capture in olfaction is minimal, as is human olfactory awareness. All this, however, does not diminish the role of olfaction through sub-attentive mechanisms allowing subliminal smells a profound influence on human behavior and perception.

Show MeSH
Related in: MedlinePlus