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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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Related in: MedlinePlus

No space for human olfactory attention. a Results from Porter et al. (2007). Humans have good allocentric olfactory abilities, and can follow a scent trail. b Scent-trail tracking speed increases with each of 4 days of practice. c Results from Porter et al. (2005). Humans have poor egocentric olfactory abilities, and are only marginally but significantly above chance at localizing the pure olfactant PEA to either the left or right of the nose. Note significantly better performance for propionic acid that has a significant trigeminal component. D. Brain mechanisms involved in extracting spatial information from smell, including the superior temporal gyrus
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Fig2: No space for human olfactory attention. a Results from Porter et al. (2007). Humans have good allocentric olfactory abilities, and can follow a scent trail. b Scent-trail tracking speed increases with each of 4 days of practice. c Results from Porter et al. (2005). Humans have poor egocentric olfactory abilities, and are only marginally but significantly above chance at localizing the pure olfactant PEA to either the left or right of the nose. Note significantly better performance for propionic acid that has a significant trigeminal component. D. Brain mechanisms involved in extracting spatial information from smell, including the superior temporal gyrus

Mentions: In contrast to the superb human spatial abilities in vision, and audition, humans have only rudimentary spatial abilities in olfaction. A critical distinction in spatial abilities is between egocentric and allocentric space. As these terms can be used differently by different researchers (Klatzky 1998), we will clearly state our use of these terms here: By allocentric abilities, we are referring to a spatial representation obtained through movement, whether of the nose alone or the entire body, within the olfactory environment. As anybody who has located a spoiled food source in the refrigerator knows, humans do have allocentric olfactory spatial abilities. Furthermore, these can be refined with practice. For example, we have found that humans can learn to track a scent-trail in a field (Fig. 2a), and they significantly improve their performance at this task with each of only four practice sessions (Porter et al. 2007) (Fig. 2b).Fig. 2


Human olfaction: a constant state of change-blindness.

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

No space for human olfactory attention. a Results from Porter et al. (2007). Humans have good allocentric olfactory abilities, and can follow a scent trail. b Scent-trail tracking speed increases with each of 4 days of practice. c Results from Porter et al. (2005). Humans have poor egocentric olfactory abilities, and are only marginally but significantly above chance at localizing the pure olfactant PEA to either the left or right of the nose. Note significantly better performance for propionic acid that has a significant trigeminal component. D. Brain mechanisms involved in extracting spatial information from smell, including the superior temporal gyrus
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2908748&req=5

Fig2: No space for human olfactory attention. a Results from Porter et al. (2007). Humans have good allocentric olfactory abilities, and can follow a scent trail. b Scent-trail tracking speed increases with each of 4 days of practice. c Results from Porter et al. (2005). Humans have poor egocentric olfactory abilities, and are only marginally but significantly above chance at localizing the pure olfactant PEA to either the left or right of the nose. Note significantly better performance for propionic acid that has a significant trigeminal component. D. Brain mechanisms involved in extracting spatial information from smell, including the superior temporal gyrus
Mentions: In contrast to the superb human spatial abilities in vision, and audition, humans have only rudimentary spatial abilities in olfaction. A critical distinction in spatial abilities is between egocentric and allocentric space. As these terms can be used differently by different researchers (Klatzky 1998), we will clearly state our use of these terms here: By allocentric abilities, we are referring to a spatial representation obtained through movement, whether of the nose alone or the entire body, within the olfactory environment. As anybody who has located a spoiled food source in the refrigerator knows, humans do have allocentric olfactory spatial abilities. Furthermore, these can be refined with practice. For example, we have found that humans can learn to track a scent-trail in a field (Fig. 2a), and they significantly improve their performance at this task with each of only four practice sessions (Porter et al. 2007) (Fig. 2b).Fig. 2

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