Olfactive short-term habituation in children and young people with profound intellectual and multiple disabilities.
Most youth with profound ID quickly tune out a repeated smell and notice a new one—rotate scents to keep learning materials salient.
01Research in Context
What this study did
The team tested 20 kids and teens with profound intellectual and multiple disabilities.
Each child smelled the same odor six times in a row.
On the seventh trial they got a new smell.
Researchers watched head turns and face changes to see if the kids stopped reacting to the old smell and woke up for the new one.
What they found
Seventeen out of twenty kids turned or changed face less by the sixth repeat.
When the new odor arrived, most kids reacted again.
This shows short-term smell habituation is intact even in profound ID.
How this fits with other research
Kumazaki et al. (2019) saw the opposite: autistic kids kept reacting to the same smell while typical kids tuned it out.
The difference is the group. Geneviève studied profound ID; Hirokazu studied ASD.
Tavassoli et al. (2012) found no smell adaptation gap in adults with autism, adding more proof that age and diagnosis matter.
Dwyer et al. (2023) used the same habituation logic with sounds and also saw weaker habituation in autistic toddlers, showing the pattern crosses senses.
Why it matters
You can now treat smell like any other habituating stimulus.
If a scent helps calm or cue, switch it often so it stays new.
If an odor seems to bother a client, give it time; the reaction may fade on its own.
Use fresh scents to regain attention during long tasks.
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02At a glance
03Original abstract
BACKGROUND: Despite its importance for learning, the existence of the habituation process and its characteristics in people with profound intellectual and multiple disabilities (PIMD) remains understudied. Habituation is, however, considered the simplest form of learning, and a significant neuroadaptive mechanism. Even though habituation occurs in all sensory modalities, the olfactory system is where it manifests itself very visibly. AIM: This study explores the olfactory short-term habituation abilities of children and young people with PIMD. METHOD: Twenty children and young people with PIMD (7-18 years) were presented six times successively with a 30-second habituating olfactory stimulus. The interstimulus interval was 15 s. A new odour was presented on the seventh trial. The scenario was carried out two times with two pairs of stimuli. The participants' head alignment duration on the odour was measured. RESULTS: Seventeen participants out of 20 manifested a decline in response, which reached about 50 % between the first and sixth presentation of the habituation odour. All habituators also showed a distinctive response when exposed to a novel odour. The participants who did not habituate showed a strong, non-fluctuating response to the stimulus throughout the presentations. Three participants only habituated to one of the two habituation stimuli. CONCLUSION AND IMPLICATIONS: The results raise theoretical, scientific, and practical issues. They question the factors explaining olfactory habituation mechanisms, namely the stimulus properties and the severity of impairment, reveal the need for points of comparison for interpreting this population's responses, and point to the consequences of stimuli repetition and or variety in therapeutic or educational settings for these individuals' learning and cognitive functioning.
Research in developmental disabilities, 2023 · doi:10.1016/j.ridd.2023.104569