sensory differences in autism

what is hyperreactivity + how is it characterised

also called hypersensitivity —> describes overwhelm at sensory input, leading to strong reactions to senses stimuli e.g. sound, light, touch, taste or smell

• may cause autistic people to escape/avoid the stimuli

• can occur as well as hyposensitivity in the same individual + can depend on factors e.g. context, mental state/levels of stress, so are not fixed or constant

what is hyporeactivity + how is it characterised

also called hyposensitivity —> describes reduced response to sensory input, leading to potentially not noticing sensations e.g. pain, temperature or sound + desire for more stimulation

• can occur as well as hypersensitivity in the same individual + can depend on factors e.g. context, mental state/levels of stress, so are not fixed or constant

why is terminology associated with sensation in autism shifting from ‘sensitivity’ to ‘reactivity’

provides a more precise focus on observable behaviour of the autistic person —> centres how a person actively/passively reacts to input rather than sensitivity level, which is more subjective

• also allows for distinction between internal neurological processes + external, observable behaviour

how did the DSM-V autism criteria change from the DSM-IV

• before the DSM-V, diagnostic criteria did not include sensory experiences —> DSM-IV’s main 3 criteria were social interaction, communication + repetitive behaviour/restricted interests

• DSM-V criteria expanded to include atypical sensory reactivity —> criteria consists of dyad of social communication + repetitive/restrictive behaviours (with sensory reactivity included within this)

are sensory issues a core part of the diagnostic criteria

• sensory reactivity is included as a subcategory under restricted + repetitive behaviours as one of 4 criteria

• as not all examples listed need to be met for a diagnosis to be made (only 2 required), it can count towards, but is not necessary to, diagnosis

• Crane found that 94% of people with ASC have sensory differences, providing evidence that vast majority do

is it just people with ASC that can have sensory differences

no - sensory differences are commonly found in those with ADHD, though this is not part of the diagnostic criteria, and some neurotypical people have also reported sensory differences

what 3 self (or caregiver) report techniques can be used to understand sensory issues in neurodevelopmental conditions

• anecdotal

• qualitative studies

• questionnaires assessing experience + behaviour

what 3 experimental techniques can be used to understand sensory issues in neurodevelopmental conditions

scores on tasks can be measured objectively, e.g.:

• psychophysical tests, e.g. measuring thresholds of perception

• visuo-cognitive tasks

what utility do qualitative studies have in investigating sensory differences in autism

aim to scientifically analyse the personal, lived experience of those with autism + organise key features into themes

what 4 questions were on the schedule for Robertson + Simmons (2015)’s qualitative research on sensory issues

• do you feel more/less sensitive to your environment than other people seem to

• do you ever have physical reactions to sensory stimuli

• are there particular aspects of stimuli that make it particularly difficult/enjoyable for you

• are visual, auditory or olfactory aspects of the environment most problematic + why

what 4 main themes emerged from Robertson + Simmons’ thematic analysis

• importance of particular aspects of stimuli in their perception

• importance of having control over stimuli

• how emotions/mental states are impacted by sensory stimuli

• physical responses to stimuli

lack of control + specific aspects both feed into emotions/mental states associated with the stimuli, leading to physical responses

what were MacLennan et al. (2022)’s findings in terms of nature of sensory reactivity

in line with previous research + anecdotal reports, autistic participants identified experiencing hyper-reactivity, hypo-reactivity + sensory seeking

• hyper-reactivity was the most commonly experienced (20.5%), followed by sensory-seeking then hypo-reactivity (only found in combination with others)

what were MacLennan et al. (2022)’s findings in terms of reactivity to 6 different senses

found general differences in perception of different senses e.g. visual, auditory, tactile, interoception, gustatory + olfactory senses

• most senses had particular stimuli that most participants were hyper-reactive to (e.g. loud noises) + sensory-seeking to (e.g. bright colours) apart from auditory + interoception

• hypo-reactivity most commonly found in response to physical pain (interoception)

what is interoception + how does it differ in autism

sensing + interpreting internal bodily cues e.g. hunger, thirst, pain + emotions

• MacLennen et al. found differences in interoception in autism → e.g. hyper-reactivity to temperature + weather change, as well as hypo + hyper-reactivity to physical pain

what are two questionnaires that measure sensory reactivity/behaviours in neurodevelopmental conditions

• Glasgow Sensory Questionnaire (Robertson + Simmons, 2009) → adults

• Sensory Profile (Brown + Dunn, 2002) → children (parental report) + adults (self report)

what is the typical disparity in scores on the GSQ

people with ASC tend to score higher on average than neurotypical participants

• measures sensory reactiivty to different senses on Likert scales

what are the results of correlating sensory issues with autistic traits

when plotting scores on the GSQ against the social responsiveness scale (scale measuring autistic traits) for neurotypical + ASC-diagnosed participants:

• in both groups, there is a positive correlation between sensory issues + autism traits scores

• some neurotypical people score higher on the GSQ than autistic people → shows variability in sensory experiences regardless of diagnostic status

• r = .808, p< .001

what are the two main subscales on the social responsiveness questionnaire (SRS)

scored on 2 subscales according to DSM-V classification:

• social-communication

• restrictive + repetitive behaviour, interests (questions about sensory experiences included on this scale)

what is found when correlating GSQ + social communication subscale of the SRS

strong positive correlation remains even when SC subscale is used instead of total score, demonstrating that the relationship between sensory issues + autistic traits does not arise as a result of common measurement error

• r = .79, p< .001

what are 4 features of the Sensory Profile questionnaire

• adult sensory profile → 60 items with questions grouped into modalities

• child sensory profile → 52 items with similar questions, adapted for parents to answer

• measures answers on Likert scale of 6 options (almost always, frequently, half the time etc.)

• people with ASC gain significantly higher scores than neurotypicals on both the child + adult versions of the scale

what 4 quadrants is the sensory profile scored on

• low registration (hypo-reactivity)

• sensation seeking

• sensory sensitivity (hyper-reactivity)

• sensation avoiding

what was the sensory profile developed for

clinical use → used by occupational + speech/language therapists, clinical + educational psychologists

what do several findings suggest regarding basic sensory functions + autism

research has found no significant difference between autistic + neurotypical participants on visual contrast, odour detection + audition sensitivity

• this suggests that basic sensory functions are intact in autism, so differences in sensory experiences are probably not rooted in fundamental differences in sensory organs

what are contrast sensitivity thresholds + what were findings in regards to autism

task assessing ability to detect difference in colours on scales of contrast + spatial frequency

• Koh et al. (2010) found no significant difference in detection ability between autistic + neurotypical participants

what is a potential explanation for sensory differences in autism

autistic people do not show differences in ability to sense stimuli, but process sensory stimuli in a different way to neurotypical people

• this results in different experience + reactivity to stimuli, while low-level sensory function is intact

what are 4 visuo-cognitive tasks that autistic people perform better at than neurotypicals on average

• embedded figures task (identifying smaller shapes in larger structures) → superior performance

• block design (rearrange blocks to calculate 2D pattern) → identified as relative strength

• ‘Navon’/hierarchical figures task → more likely to have locally than globally-oriented perception (what NTs usually have)

• visual search → faster performance

what general conclusions are drawn from superior results on visuo-cognitive tasks + what theory does this support

cognitive tasks that require participants to identify local over global elements in a scene are generally performed more quickly + accurately by autistic people

• finding underpins theories of autistic cognition e.g. ‘weak central coherence’ hypothesis (though these are considered a bit simplistic now)

what do findings from other visual tasks generally point to + what are limitations to this conclusion

there is evidence for altered thresholds to different cognitive abilities in autism (both reduced + enhanced)

• however these findings have limited replications + have been found in many conditions, so are not unique to autism

• most

what 2 cognitive skills have people with autism been found to have heightened thresholds for

reduced discrimination for:

• coherent motion

• hue

what is the most consistent finding for altered thresholds in autism (Milne et al., 2002)

reduced motion coherence discrimination→ means that more objects need to be moving cohesively for motion coherence to be detected in those with ASC

• those with autism have higher threshold for being able to detect it

what 2 cognitive skills have people with autism been found to have reduced thresholds for

enhanced discrimination of:

• orientation (Bertone et al., 2005)

• detection of symmetry (Perrault et al., 2011)

what does having a low threshold for orientation discrimination mean + what does this mean for people with autism

the lower the threshold, the better the orientation discrimination → means the smaller change needed to be able to detect a different angle

• studies have found lower thresholds correlated with higher AQ scores

what is the association between performance on visual tasks + sensory experiences

there is no correlation between visual task performance + self-reported sensory experiences → shows no association between these 2 variables

what are 3 possible reasons for the lack of correlation between methods of assessing sensory differences

• questionnaires that measure sensory experiences are likely not nuanced enough to provide a very accurate measurement → e.g. rarely take into account impact that stress/control has on sensory experience

• there may be different mechanisms underpinning different experiences → e.g. mechanisms that drive orientation discrimination may be different to mechanisms that drive sensory behaviour

• the role of attention/focus is generally not considered

what is the potential role of attention in autistic perception + what two consequences does this lead to

people with autism may have a broader attentional spotlight, which may underpin:

• superior visual search skills

• lead to difficulty filtering out distracting stimuli

what is monotropism

a very focused attentional state, which is often discussed by people with autism

on what 3 aspects of visual search do people with ASC have an advantage on (Plaisted et al., 1998)

faster response time:

• when performing conjunctive searches → when target is defined by combination of two or more features

• when target is absent

• when search task is difficult

what were the two main aspects of Milne’s study on feature-based selective attention

participants with either high or low scores on the AQ had to:

• perform a visual search task with distractors of varying similarity to the target on measures of colour + orientation

• be measured via EEG on neural markers for attention allocation

how did the measured ERP vary in Milne’s study

the amplitude of the measured ERP (P3b) varied depending on how similar distractors were to the target → when distractors were more similar, there is a larger amplitude around 400ms after stimulus onset

• this implies increased allocation of attention to the distractor

what were Milne’s findings in terms of visual search score + ERP response

• participants with higher AQ scores were quicker at the visual search task than those with lower AQ scores

• participants with higher AQ scores generated larger P3b amplitudes to distracting stimuli than the low AQ group

what was the main conclusion from Milne’s study

greater allocation of attention to distractors may be a neural marker for altered attention in autism

what were the 4 (actual???) themes that MacLennan et al. (2022) identified from their thematic analysis

• outcomes

• control

• tolerance + management

• the role of other people

what style of research did MacLennan et al. (2022) conduct

a mixed-method design using data collected from online surveys in order to investigate the sensory experiences in adults with autism

• 49 participants were included in the study, though not all participated in the additional open questions

what are 5 sensory experiences that MacLennan et al. (2022) identified autistic people as being commonly hyperreactive to

• loud (87.5%) + high-pitched (77.5%) sounds

• bright + flashing lights (75%)

• complex sounds e.g. lots of conversation (82.5%) + public transport (70%)

• music (75%)

• different textures (62.5)

what are 3 sensory experiences that MacLennan et al. (2022) identified autistic people as being hypo-reactive to

• physical pain (30%)

• hot (15%) + cold (12.5%) temperatures

what are 5 sensory experiences that MacLennan et al. (2022) identified autistic people as commonly seeking

• music (60%)

• different textures (73.5%)

• patterns (35%) + bright colours (30%)

• feeling pressure differences (32.5%)

• favourite/spicy food flavours (37.5%)

what was found in the ‘outcomes’ theme of MacLennan et al. (2022)’s research

• negative impacts on mental health, e.g. causing stress + anxiety, as well as being linked to maladaptive behaviours e.g. self-harm + eating disorders

• physical outcomes of hyperreactivity e.g. physical pain + nausea, as well as affecting sleep or nutrition

• overwhelm due to sensory input causing people to disengage

what 4 subthemes were found in the ‘tolerance + management’ theme of MacLennan et al. (2022)’s research

• avoidance/escaping aversive sensory input as a coping strategy, such as leaving the physical environment or physical blocking behaviours

• adaptations to different environments e.g. sunglasses/headphones or sensory reactivity becoming more tolerable overtime

• soothing sensory input in order to cope with distress

• extent of sensory reactivity = dependent on mood → may not be as bad if more relaxed

what 2 subthemes were found in the ‘control’ theme of MacLennan et al. (2022)’s research

• desire for control + predictability → causes difficulty with unpredictable stimuli

• difficulty with self-control when it comes to engaging with enjoyable sensory experiences

what 2 subthemes were found in the ‘role of other people’ theme of MacLennan et al. (2022)’s research

• understanding → often compare themselves to others who seem to have differences in sensory reactivity to them

• support from other people lessened experience of sensory reactivity