sense of smell
Enable an agent to recognise olfactory capacity and experience, assess what observations support about their state, and choose appropriate further observation or support.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an agent to recognise olfactory capacity and experience, assess what observations support about their state, and choose appropriate further observation or support.
The sense of smell, or olfaction, is the sensory capacity to detect and discriminate chemical stimuli through olfactory receptors and neural processing, supporting odour perception and behaviour.
It can be Separate detection, discrimination, identification and subjective experience within an assessment record.; Compare repeated observations when stimulus delivery, task and context are sufficiently compatible.; Identify missing controls or contextual information before interpreting an apparent olfactory change.; Represent smell contributions to food experience while linking taste and flavour to neighbouring models.; Record uncertainty and route consequential interpretations to appropriate human review.; Identify activities that rely on smell and document alternative cues when olfactory evidence is insufficient..
Distinguishing features
Establish whether the record concerns an organism's sensory capacity or experience, rather than merely an airborne chemical concentration.
Separate odour detection from naming: detecting that samples differ can support olfactory performance even when the organism cannot provide an odour label.
For food-related reports, distinguish olfactory evidence associated with the retronasal route from taste and other contributors to flavour.
Determine whether an apparent smell response could instead reflect irritation, cooling, visual cues or learned task cues.
Distinguish capacity across repeated observations from the intensity or character of one reported smell episode.
Scope
+ Olfactory capacity attributed to an identified organism and assessed under specified conditions
+ Episodes of odour detection, discrimination, identification and perceived intensity
+ Orthonasal and retronasal routes and their contributions to reported experience
+ Changes in olfactory performance or experience over time
+ Evidence linking odour perception to context, learning and practical decisions
- Chemical composition and emission behaviour of odorant substances
- Detailed anatomy and molecular mechanisms of olfactory organs and pathways
- Taste and the complete multisensory experience of flavour
- Trigeminal sensations such as nasal irritation, cooling or burning considered independently
- Diagnosis and treatment of diseases associated with altered smell
- Electronic noses and chemical sensors that do not constitute organismal perception
Characteristics
- Sensory bearer
- Identified organism; species; relevant reporting or behavioural capabilities Human verbal identification tasks cannot be assumed to measure smell comparably in every organism.
- Assessment target
- Capacity; individual perceptual episode; change in capacity; change in experience A single experience and a persistent sensory capacity require different evidence.
- Odorant access route
- Orthonasal; retronasal; mixed; unspecified Route helps distinguish environmental smelling from smell contributions during eating.
- Detection threshold
- Protocol-specific concentration or dilution step, with odorant, delivery conditions and detection criterion A threshold is interpretable only with the stimulus and procedure that produced it.
- Odour discrimination performance
- Correct responses per trials or protocol score, with task alternatives and chance level Discrimination measures whether odours can be distinguished without requiring correct names.
- Odour identification performance
- Correct responses per trials or protocol score, with language, familiarity and response format Identification combines sensory evidence with learning and task demands.
- Perceived intensity and quality
- Intensity on a named scale plus participant-provided or controlled-vocabulary quality descriptors Stimulus concentration does not substitute for a record of perceived experience.
- Reported olfactory state
- Usual for bearer; reduced; absent; heightened; distorted with stimulus; reported without identified stimulus; uncertain Preserves the kind of reported change without turning the report into a diagnosis.
- Temporal and exposure context
- Onset, duration, recurrence, recent exposures, recovery intervals and comparison baseline An observation may reflect temporary exposure effects or a longer-lasting change.
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 30 questions.
Olfactory identity Defines the sensory capacity or episode being represented and its boundaries.
Smell is easily conflated with odorant presence, flavour, irritation or successful naming.
Capacity and episode
Separates a bearer's capacity from an occurrence of smelling.
Bearer and assessment target
Record whose smell is represented and whether the evidence concerns an episode, a capacity or a change.
- Does this record concern an olfactory capacity, one smell experience or a change relative to an earlier state? definition
- Whose observation or behavioural record supports attributing this capacity or episode to the organism? provenance
Sensory boundaries
Distinguishes olfaction from neighbouring sensory contributions.
Olfaction versus associated cues
Keep smell evidence separate from taste, irritation and contextual cues while allowing linked multisensory experiences.
- What supports interpreting the response as olfactory rather than a response to taste, irritation or a visible cue? boundary
- If the report concerns flavour, which part is attributed to smell and which parts remain assigned to neighbouring senses? boundary
Odorant access and exposure Captures how and under what conditions a candidate odour reaches the organism.
An apparent difference in smell can arise from exposure or delivery differences rather than sensory capacity.
Delivery route
Records the route and presentation conditions of the stimulus.
Route and sampling
Represent orthonasal or retronasal access together with relevant sampling conditions.
- Was the candidate odour encountered through orthonasal smelling, retronasal access during eating or an unresolved combination? measurement
- Were presentation duration, delivery method and any nostril-specific conditions recorded? provenance
Exposure history
Records stimulus background and recent exposure relevant to interpretation.
Background and repetition
Track background odours, repeated presentations and intervals without assuming why perception changed.
- What background odours and preceding presentations could affect the current observation? measurement
- What comparison would help distinguish an exposure-related change from a persistent change in capacity? action
Olfactory performance Separates the tasks through which olfactory capacity is operationalised.
Detection, discrimination and identification answer different questions and should not collapse into one unspecified smell score.
Detection and discrimination
Represents noticing an odour and distinguishing odours without requiring names.
Task-specific sensitivity
Retain task design, stimulus levels and uncertainty alongside observed performance.
- Was the organism asked to detect an odour against a blank or distinguish between odorant samples? definition
- What stimulus levels, trial counts, response criterion and chance performance define the result? measurement
Identification and comparability
Captures recognition and naming while preserving their interpretive limits.
Identification task demands
Record familiarity, language and response format before interpreting identification performance as evidence about sensory capacity.
- Did the task require free naming, choosing a label or matching an odour to a familiar source? measurement
- Are the language, odour familiarity, protocol and reference population compatible with the proposed comparison? boundary
Olfactory experience and meaning Represents what smelling is like and how the bearer interprets it.
Performance scores alone do not describe odour quality, pleasantness or the meaning assigned to an experience.
Perceptual description
Records subjective intensity and quality without treating descriptors as chemical identification.
Quality, intensity and valence
Preserve the bearer's descriptions and scales separately from observer interpretations.
- How did the bearer describe the odour's quality, intensity and pleasantness, and using which scales or vocabulary? measurement
- Which statements are direct reports, and which are an observer's interpretations of behaviour? provenance
Recognition and association
Distinguishes source attribution and learned associations from the sensory report.
Perceived source and learned meaning
Represent familiarity, memories and attributed sources without treating association as source verification.
- What source, memory or significance does the bearer associate with the odour? definition
- What evidence independently supports the attributed source beyond resemblance or familiarity? provenance
Change and practical response Tracks altered smell and the decisions that depend on interpreting it.
An agent needs to preserve uncertainty about sensory change while identifying affected activities and justified next steps.
Olfactory change
Represents the pattern, timing and evidential status of a change.
Change from baseline
Distinguish reduced detection, changed odour quality and experiences without an identified stimulus; retain reports and measured results separately.
- Relative to which baseline is smell reported or measured as reduced, absent, heightened or distorted? measurement
- What is known about onset, persistence, recurrence and the presence of an external stimulus? provenance
- Which causal explanations remain unresolved and belong to a linked assessment rather than this sensory-state record? boundary
Smell-dependent decisions
Connects olfactory evidence to affected activities and proportionate follow-up.
Functional reliance and next observation
Record which decisions depend on smell, what corroboration they require and whether further observation or human review is appropriate.
- Which activities, such as enjoying food, recognising environmental odours or performing an occupational task, are affected? measurement
- What additional observation, alternative cue or qualified human review is needed before acting on this smell report? action
- Does the proposed decision exceed what detecting or failing to detect this odour can establish? boundary
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- This account primarily describes human olfaction; receptor systems and ecological functions differ across species.
- Orthonasal and retronasal olfaction are routes of stimulation, not separate receptor senses.
- These statements are recalled knowledge, not source-verified findings; numerical thresholds and clinical interpretations require odorant-specific and test-specific references.
- Which of these check these first hold for the sense of sense of smell this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Orthonasal olfaction: sensing odorants entering the nasal cavity from the external environment
- Retronasal olfaction: sensing odorants reaching the nasal cavity from the mouth during eating and drinking
- Which of these kinds and varieties hold for the sense of sense of smell this model covers, and on what evidence? provenance
Identifiers and schemes
Recalled without web access and unsourced; every item is a lead to verify.
- Gene Ontology - GO:0007608 - The biological-process term 'sensory perception of smell'; it identifies a process rather than an individual's sensory ability.
- Which of these identifiers and schemes hold for the sense of sense of smell this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Contributing to flavour perception and food selection
- Detecting environmental cues such as smoke, spoilage and added fuel-gas odorants
- Assessing fragrances, foods and beverages through sensory evaluation
- Assessing olfactory function using detection, discrimination and identification tasks
- Supporting navigation, foraging and chemical communication in many animals
- Which of these real-world use hold for the sense of sense of smell this model covers, and on what evidence? provenance
Typical measurements
Recalled without web access and unsourced; every item is a lead to verify.
- Odour detection threshold - Varies widely with odorant, individual and test protocol; there is no universal normal concentration range. - Odorant concentration, such as parts per billion by volume in air
- Odour identification performance - From zero to all items correct; interpretation depends on the test, age and familiarity with its odours. - Correct responses or percentage correct
- Odour discrimination performance - Protocol-dependent; assessed relative to chance performance and test-specific reference data. - Correct responses or percentage correct
- Which of these typical measurements hold for the sense of sense of smell this model covers, and on what evidence? provenance
Failure modes and hazards
Recalled without web access and unsourced; every item is a lead to verify.
- Anosmia or hyposmia: absent or reduced smell function
- Parosmia: distorted perception of an odour that is present
- Phantosmia: odour perception without a corresponding external odorant stimulus
- Adaptation during continued exposure can reduce perceived odour intensity and make smell an unreliable warning signal.
- Some dangerous substances, including carbon monoxide, are odourless; odour intensity does not reliably indicate toxicity.
- Which of these failure modes and hazards hold for the sense of sense of smell this model covers, and on what evidence? provenance
Regional variation
Recalled without web access and unsourced; every item is a lead to verify.
- Odour identification depends partly on cultural familiarity, language and exposure, so test materials and reference data may require local validation.
- Odour descriptions, preferences and acceptable environmental odour levels vary across communities.
- Which of these regional variation hold for the sense of sense of smell this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- Taste - Taste involves gustatory receptors and qualities such as sweet, sour, salty, bitter and umami; smell involves olfactory receptors.
- Flavour perception - Flavour integrates retronasal smell with taste and other oral sensations; olfaction is one contributing sensory system.
- Chemesthesis - Chemical burning, cooling and irritation arise through somatosensory pathways rather than olfactory signalling, although one substance can stimulate both.
- Odour - An odour is a perceived smell quality or the stimulus described as producing it; the sense of smell is the capacity that detects and processes it.
- Chemical communication - Chemical communication concerns signals between organisms; olfaction also detects environmental chemicals that are not communicative signals.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of sense of smell this model covers, and on what evidence? provenance
What the second pass must settle
- Which existing Vercy perception or olfaction model, if any, already owns this concept and should be linked instead of duplicated?
- Which reference definitions best reconcile smell as sensory capacity, perceptual process and conscious experience, particularly across species?
- Which assessment protocols and reference populations support defensible comparisons across age, language, culture and species?
- What evidence and observation intervals are sufficient to distinguish temporary exposure effects from persistent olfactory change?
- How should conflicting subjective reports, behavioural results and stimulus measurements be represented without assigning unsupported diagnostic or causal labels?