Can sensory discrimination ability in children with low functioning autism be used as an index of cognitive ability—an exploratory study

Abstract

This study purports to bridge the gap in research directed at people with Low Functioning Autism (LFA) by exploring if sensory discrimination ability can be used to assess cognitive functioning in children with LFA. The study was done in two phases: (i) a pilot phase (with 4 male participants; mean age = 3 years 6.5 months)—which tried to validate whether the paradigm of ‘visual paired comparison’ procedure (Fantz, Science, 146, 668–670, 1964) can be effectively used in measurement of perceptual judgment of LFA, diagnosed on the basis of ‘Autism Diagnostic Checklist’ by Banerjee (Indian Journal of Clinical Psychology, 34, 83–93, 2007). (ii) A main phase (with 20 participants; male = 18, female = 2; mean age = 4 years 8 months)—which determined sensory discrimination ability in LFA in the auditory and visual modality and related the findings with the sensory threshold of the children by using ‘The Sensory Profile’ (Kumar and Banerjee, Development of sensory integration therapeutic module for autism and its effect on some functional areas of autism. Unpublished Ph.D Thesis, 2011). The results reveal that the ‘Visual Paired Comparison’ paradigm can be used as a tool to discern sensory discrimination ability in children with Low Functioning Autism. Also, sensory discrimination can be used to differentiate the cognitive ability of children with Low Functioning Autism. The behavioural repertoire of sensory discrimination is associated with the sensory threshold of the participants.

Introduction

The notion that ‘sensory discrimination’ abilities are linked to intellectual processes dates back to the time of Galton (1883). Galton had hypothesized that one of the fundamental basis of intelligent activity can be traced into fine differences in sensory discrimination ability; which in turn is due to heritable aspects in the development of the nervous system. Later theorists like Spearman (1904) and Cattell and Krugg (1986) were inspired by Galton’s proposition. In the quest for an universal and all pervasive index of intellectual functioning, Spearman (1904) considered sensory discrimination as the simplest form of intellectual operation. Raz et al. (1987) had proposed that high intelligence is associated with greater resolution in sensory processing. Infact, Raz et al. (1983) obtained significant correlation between tests of pitch discrimination and Cattel’s Culture Fair Test of intelligence. Subsequently, Acton and Schroeder (2001) examined sensory and cognitive processing in a very large sample of 899 adults with above average intelligence. They also found a modest significant correlation between sensory discrimination tests and tests of general intelligence. These researchers opined that processing speed is a basic cognitive parameter mediating sensory discrimination and intelligence. In a relatively recent research, Rammsayer (2014) is of the opinion that one possible cause for the higher speed of information processing of more intelligent individuals may be that higher-intelligence scores are associated with higher temporal resolution capacity of the brain.

Autism spectrum disorders (ASD) are a heterogeneous group of neuro-developmental disorders which are predominantly characterized by impairments in reciprocal social and emotional interaction and repetitive and rigid behaviours (APA, DSM—5th ed., 2013). Since the early 1940s, when Kanner (1943) codified the phenomenon of autism, there has been innumerable research directed at teasing apart the multifarious factors that influence the expression of autism (Chaste and Leboyer 2012). But, unfortunately, all such research has been conducted on individuals belonging to the so-called ‘high functioning’ (HFA) end of the autism spectrum who apparently do not show any significant impairment of language. Individuals with ‘low functioning autism’ (LFA) have been inadvertently left out of such research endeavours because of their predicament of deficit in spoken language.

The issue of cognitive assessment and autism has always been a kind of oxymoron; because a psychometric test situation is typically a social situation where dyadic communication between the tester and the testee is a mandatory prerequisite. In the present study, ‘Low Functioning Autism’ or LFA has been operationalized as individuals with autism and associated mental retardation and predominant language deficits. On the other hand, ‘High-functioning autism’ or HFA has been used to refer to individuals with the triad of autism diagnostic impairments whose current levels of cognitive functioning and language, despite their intrinsic oddities are relatively less pathological in comparison to their low functioning peers. Thus the term includes people with ‘Asperger syndrome’. However, it should be kept in mind that this distinction between HFA and LFA is purely nosological and based on academic considerations.

It is now widely recognized that the incidence of Autism Spectrum Disorders has increased manifold in the last few decades (Karanth et al. 2010). Hence, it is imperative to develop instruments to understand the cognitive potential of individuals with severe to profound levels of autism (LFA). This study purports to determine if—(a) measures of sensory discrimination can reliably be used as an index of cognitive ability in children with LFA; (b) visual selective attention paradigm used for the assessment of basic cognitive functions in preverbal infants can be adopted for LFA who have similar inabilities in expressive language

Methods

Deciding on the method of data collection

It is quite a challenging task for the psychometrician to arrive at a meaningful inference regarding the cognitive ability of children with severe to profound autism. LFA is generally unpredictable research participants with limited linguistic skills and unusual repertoire of interests that makes their attention span either too short or too difficult to disengage from a stimulus. In a similar vein, the task of assessing cognitive abilities in infants are equally arduous and the researcher typically relies on the observation of the infant’s nonverbal behaviours as an index of the cognitive function under consideration. The Visual Paired Comparison task (VPC), though originally designed to study perception in developing primates (Fantz 1958); have been successfully adapted for assessing visual recognition memory in infants (Fantz 1964). The VPC exploits the phenomenon of ‘visual selective attention’ and ‘novelty preference’ as the mechanism for explaining infant memory. In the classical paradigm of VPC, when participants look longer at the novel stimulus than at the familiar (target) stimulus during the test (i.e. exhibit a novelty preference), it is inferred that they have shown ‘retention’ of the target stimulus. Such interpretations are derived from Sokolov’s (1963) theorization of the ‘orienting response’; wherein novel stimuli elicit an orienting response; visual fixation is one component of that orienting response. The LFA in this study might be unresponsive to verbal stimuli, but they tend to display responsiveness to a variety of sensory stimuli and in their own precocious way are engaged in exploring the environment. It was noted that their response repertory can be categorized into

• looking for a longer time at some stimuli in comparison to other stimuli

• trying to touch the source of some stimuli and not other stimuli

• not showing any overt approach behaviour to some stimuli as contrasted with other stimuli

It is worth mentioning that these categories of ‘other stimuli’ are those with less intensity; be it auditory or visual.

Sample

The participants of the study were screened for the presence of Autism Spectrum Disorder. The screening was done either by postgraduate or M. Phil students of the Department of Psychology, who undergo training for the detection and management of autism and allied developmental disabilities. The diagnosis was additionally confirmed by the researcher who is a trained Clinical Psychologist. The screening and/or diagnosis was done using the standard Mayer and Gross format (Klein and Mayer-Gross 1957) for clinical examination, modified and suited to the clinical setting under consideration and using the criteria laid down by Diagnostic and Statistical Manual version IV (DSM IV, APA, 1994). The children with LFA who were the participants of the study were selected from two sources: (i) The Department of Psychology, University of Calcutta; children who are regularly referred to the department by Government Hospitals and private practitioners for psychological assessment; which forms a part of the practical curricula for post graduate students pursuing Clinical or Developmental Psychology and M. Phil students and (ii) Pradip Centre for Autism Management; a non-government, non-profit organization in Kolkata that provides special education and intervention to children with developmental disabilities. The Autism Diagnostic Checklist (Banerjee 2007) was used to substantiate the diagnosis and to have an index of the level of autistic features. All the child participants in the study belonged to the category Mild to Moderate Level of Autism.

Sample for the pilot phase

4 male children with a mean age of 3 years 6.5 months andmild to moderate autism were selected for the study to explore if the VPC paradigm can be adopted for assessing perceptual abilities in children with LFA

Sample for the main phase

The participants of the main phase of the research were 20 (18 = male; 2 = female) children with a mean age of 4 years 8 months and with mild to moderate autism and developmental age equivalent to receptive language <9 months.

Measures designed or used for the study

An apparatus for visual discrimination

A very simple apparatus was prepared for the visual discrimination task. It consisted of a regular plug and socket electric board which could be connected to any external source of power. On the board were mounted two sockets for bulbs, spaced about 8 inches apart and a regulator with each point. The regulators would change the intensity of light emanating from each bulb just in the same way they are actually used to control the speed of a moving fan. There are 4 levels of intensity akin to the position of the regulators. For the purpose of the study standard 60 watt white coloured halogen light was used. Also the intensity of light was pre-fixed at ‘1’ for low intensity and ‘4’ for high intensity.

An apparatus for auditory discrimination

Again, a much uncomplicated apparatus consisting of two wireless speakers with in-built volume control and USB port was used. The sound of a cat meowing was downloaded from the Internet and input in the two speakers via the USB. The two speakers were spatially separated at a pre-fixed distance (8 inch apart). The volume of the speakers was adjusted to a pre-fixed maximum and minimum

Assessment of level of language development

The 3D Language Test by Herlekar and Karanth (1995) was incorporated in the study during the second phase of data collection to get a comprehensive index of the delay/deficit in acquisition of expressive language abilities.

Assessment of sensory profile

Research has repeatedly pointed out that children with ASD have idiosyncratic ways of processing sensory stimuli (Brown and Dunn 2010; Pollock 2009) and such unusual processing influence the manner in which the child relates with the external world (Koenig and Rudney 2010; Robinson and Magill-Evans 2009); which can also have a functional impact on the child’s sensory discrimination ability. Hence, ‘The Sensory Profile’ developed by Kumar and Banerjee (2011) was included as an additional measure in the second phase of the research in order to measure the child’s responses to sensory events in everyday life that support or interfere with function. The entire scale was administered, but for the purpose of the present research, only the domains ‘visual’ and ‘auditory’ were scored. The data was collected from the primary caregiver and corroborated by the observation made by the researcher regarding the behaviour of the child.

Inclusion of video recording of the data collection sessions

Systematic observation and analysis of home videos of infants who are later diagnosed with autism have proven to be another source of information on sensory issues in autism (Losche 1990). Hence, video recording of the entire data collection event for each participant was done, with prior consent from the caregivers/guardian of the child with autism.

The recording of video was done using an android mobile phone with video recording facility (with a precision of at least 15 megapixels). The data was subsequently transferred to the computer, via a data cable.

Systematic observation procedure

The process of observation entailed noting the frequency of particular behaviour patterns and how these behaviours unfold over time in the context of the presence of the stimulus. On the basis of the research literature dealing with systemic observation of children with developmental disabilities, the following non verbal behaviours were coded in terms of their frequency

• gaze—looking at or avoiding eye contact with researcher and/or stimulus

• body movement—touching, approaching/withdrawal, repetitive stereotypical movements like hand flapping, diminished activity level like posturing etc.

• facial expression—wincing, furrowed brow, widened eyes, tearfulness, crying, frowning, (inappropriate) smiling

To ensure inter-observer reliability, the observation of the behavioural response of each child was simultaneously done by the main researcher and one of her research scholars and the mean score for each behaviour was taken into consideration.

Subsequent analysis of the coded behaviours revealed that in the context of the research question, the behaviours displayed by the children with LFA can be pigeon-holed into 3 categories—(a) behaviours reflecting an interest to explore the stimulus, (b) behaviours reflecting that the stimulus is perceived to be obnoxious and (c) behaviours displaying a listlessness akin to indifference towards the stimulus. Congruent with our initial theoretical considerations, the afore-mentioned behaviours were conceptualized under three paradigms, viz.

1. Approach

2. Withdrawal

3. Apathetic

Procedure

Each participant was tested individually in a quiet room at the Department of Psychology, University of Calcutta and accompanied by a caregiver, usually the participant’s mother. The rationale of the testing procedure was explained to the concerned caregiver prior to the acquisition of the data. This ensured that the caregivers would remain as non-intrusive and non-participating in the testing sessions as possible. Testing was done over one to two sessions and was limited to a maximum of 30 min per session. The total testing time varied between 20 min and 1 h depending on the participant’s abilities.

Pilot phase

The aim was to find out whether these children could make basic sensory discrimination and to find out how such discriminatory abilities, if present, translate into behaviour. The discrimination task entailed a paired presentation of two stimuli, belonging to the same modality, but differing in intensity. For the ‘visual discrimination task’, as well as the ‘auditory discrimination task’, the intensity of the stimuli, in terms of their spatial location, were varied according to the following schedule so that error of anticipation and error of habituation could be ruled out. Accordingly 10 responses for each subject were recorded.

	Right bulb	Left bulb		Right speaker	Left speaker
Intensity of light	High	Low	Intensity of sound	High	Low
	Low	High		Low	High
	Low	High		Low	High
	High	Low		High	Low
	Low	High		Low	High
	High	Low		High	Low
	High	Low		High	Low
	Low	High		Low	High
	High	Low		High	Low
	Low	High		Low	High

Main phase

The procedure outlined in the ‘pilot study’ section was followed for the acquisition of data regarding the participants’ response to sensory stimuli of auditory and visual modality and of varying intensity. However, it was evident from the ‘pilot study’ that it was difficult to engage children with LFA in a task for long. Hence, the number of observations for each stimulus pair, for each modality was reduced to 6 instead of 10. The schedule which was followed for the presentation of the sensory stimuli were as follows:

	Right bulb	Left bulb		Right speaker	Left speaker
Intensity of light	High	Low	Intensity of sound	High	Low
	Low	High		Low	High
	Low	High		Low	High
	High	Low		High	Low
	Low	High		Low	High
	High	Low		High	Low

Statistical analysis

The variables in the study are nominal variables. Hence, the statistical analysis involved analysis of frequencies. There were 3 such nominal variables:

Sensory profile of the participants—which is divided into 2 categories viz. high threshold and low threshold; scored separately for visual and auditory modality

Response repertoire of the participants—which is divided into 3 categories viz. approach, withdrawal and neutral

Discriminatory sensory stimulus—which is divided into 2 categories viz. high intensity and low intensity; assessed separately for auditory and visual modality

As has been already stated, each observation consisted of a paired presentation of sensory stimuli (of high and low intensity) of a particular modality (auditory as well as visual); whereby the spatial location of the high intensity and low intensity stimulus was arranged following an ABBA paradigm, to nullify errors of anticipation and habituation. Each observation required 2 responses from the participants, each with respect to the two stimuli presented. Hence for each participant, repertoires of 12 responses were recorded. There were 20 participants, who were also categorized into 2 groups on the basis of their sensory thresholds.

The statistical analysis entailed calculation of the frequencies of different dimensions of responses towards a high intensity and towards a low intensity stimulus. Chi square analysis was done manually to find out if the response categories have a functional association with the intensity of the stimulus and with the sensory thresholds of the participants.

Ethical considerations

The research protocol was screened by the Department Ethical Committee as well as the Ethical Committee of the University Grants Commission (UGC) Special Assistance Program (SAP). Informed consent was taken from the primary caregivers of the child participants. The nature and purpose of the study, absence of any immediate psycho-social/medical/financial benefit for participation, freedom to exit from the research without any detrimental consequences for the child etc. were explained. Collection of data was discontinued as and when a child’s behaviour was suggestive of the child experiencing distress.

Results

Results of the pilot study

The participants in the pilot study were all males with a mean age of 3 years and 6.5 months (age range : 2 years 10 months to 4 years 5 months) with a diagnosis of Moderate Autism as per the ADCL (Banerjee 2007) (please refer to Table 1).

Table 1.

Showing the distribution of clinical data of the subjects.

Subject no.	Age	Sex	Diagnosis	Developmental milestones	Language present
1	3 years 2 months	Male	Autism	Delayed	No
2	4 years	Male	Autism	Delayed	No
3	2 years	Male	Autism	Delayed	No
4	5 years	Male	Autism	Delayed	No

It is evident from the results cited in Table 2 and Table 3 that the subjects displayed unique response patterns to variable stimulus attributes (intensity) which can be classified as

1. approach behaviour suggestive of interest towards the stimulus

2. withdrawal behaviours suggestive of perception of stimulus as unpleasant and

3. neutral behaviours which can neither be described in terms of approach nor in terms of withdrawal and is indicative of disinterest towards the stimulus

Table 2.

Response of the subject on visual discrimination task

Number of subject	Number of observation	Discriminatory response of the subject in terms of approach/withdrawal	Qualitative description of the response
1	1	Approach	Tries to touch the light with greater intensity and often tries to put it in the mouth
	2	Withdrawal
	3	Approach
	4	Approach
	5	Withdrawal
	6	Withdrawal
	7	Approach
	8	Withdrawal
	9	Withdrawal
	10	Withdrawal
2	1	Approach	Looks for a longer period of time towards the light with greater intensity
	2	Withdrawal
	3	Approach
	4	Approach
	5	Withdrawal
	6	Approach
	7	Approach
	8	Withdrawal
	9	Withdrawal
	10	Withdrawal
3	1	Withdrawal	Tries to grab the bulb that has higher intensity
	2	Withdrawal
	3	Withdrawal
	4	Approach
	5	Approach
	6	Approach
	7	Approach
	8	Withdrawal
	9	Approach
	10	Withdrawal
4	1	Approach	Stares at the bulb with higher intensity and bangs the bulb
	2	Withdrawal
	3	Withdrawal
	4	Approach
	5	Withdrawal
	6	Approach
	7	Approach
	8	Withdrawal
	9	Approach
	10	Approach

This table tries to describe the response/behaviour of each of the four participants (of the pilot study) to the visual sensory stimulus with differential attributes.

Table 3.

Responses of the subject on auditory discrimination task

Number of subject	Number of observation	Discriminatory response of the subject in terms of approach/withdrawal	Qualitative description of the response
1	1	Approach	Smiles when the cat meows and moves towards the speaker set at high intensity
	2	Withdrawal
	3	Withdrawal
	4	Approach
	5	Withdrawal
	6	Approach
	7	Approach
	8	Withdrawal
	9	Approach
	10	Withdrawal
2	1	Approach	Smiles when the cat meows and tries to grab the speaker set at higher volume
	2	Withdrawal
	3	Withdrawal
	4	Approach
	5	Withdrawal
	6	Approach
	7	Approach
	8	Withdrawal
	9	Approach
	10	Withdrawal
3	1	Approach	Looks towards the speaker which plays the meow more loudly
	2	Withdrawal
	3	Withdrawal
	4	Approach
	5	Withdrawal
	6	Approach
	7	Approach
	8	Withdrawal
	9	Approach
	10	Withdrawal
4	1	Approach	Takes hold of the speaker with the loud meow and tries to put it in the mouth.
	2	Withdrawal
	3	Withdrawal
	4	Approach
	5	Withdrawal
	6	Approach
	7	Approach
	8	Withdrawal
	9	Approach
	10	Withdrawal

This table tries to describe the response/behaviour of each of the four participants (of the pilot study) to the auditory sensory stimulus with differential attributes.

Result of the main study

The participants of the main study consisted of 20 children with Low Functioning Autism; 18 being male and 2 being females. 8 of the children had Mild Autism and 12 of the children had Moderate Autism. The assessments of the level of autism were done on the basis of the ADCL (Banerjee 2007). The age range of the participants were from 3 years 10 months to 5 years 8 months with a mean age of 4 years 8 months. (please refer to Table 4).

Table 4.

Demographic details of the participants.

Variables		Mean/Frequency (percentage)
Chronological age	Range = 3 years 10 months to 5 years 8 months	4 years 8 months
Sex	Male	18 (90)
	Female	2 (10)
Age equivalent of receptive language development		<9 months
Severity of Autism Symptoms	Mild	8 (40)
	Moderate	12 (60)

Majority of the participants belonged to the High Sensory Threshold for both visual and auditory modality (please refer to Table 5).

Table 5.

Distribution of the sensory profile of the participants across auditory and visual modality.

Domain	High threshold	Low threshold
	f (%)	f (%)
Visual	12 (60)	8 (40)
Auditory	11 (55)	9 (45)

The analysis reveals that there is a significant association between frequency of a particular response pattern and intensity of the visual stimulus; the children clearly showing increased approach behaviour towards stimulus of higher intensity (please refer to Table 6).

Table 6.

Distribution of frequencies of different responses across high intensity and low intensity stimulus of visual modality.

Responses (frequency)	High intensity	Low intensity	Percentage	Total	Chi square
Approach	101	39	58.33	140
Withdrawal	32	19	21.25	51
Neutral	22	27	20.42	49	12.13
Total	155	95	100	240	Significant p < 0.01

The analysis reveals that a significant association also exists between frequency of a particular response pattern and intensity of the auditory stimulus. Here also, increased approach behaviour of the participants was evident towards the stimuli with higher intensity (please refer to Table 7).

Table 7.

Distribution of frequencies of different responses across high intensity and low intensity stimulus of auditory modality.

Responses (frequency)	High intensity	Low intensity	Percentage	Total	Chi square
Approach	95	38	55.42	133
Withdrawal	20	7	11.25	27
Neutral	32	48	33.33	80	22.64
Total	147	93	100	240	Significant p < 0.01

There is a significant association between the category of sensory profile to which the child belongs to and the pattern of behaviour shown by the child to the visual stimuli of varying intensity; higher frequency of approach behaviour being present in children with high sensory threshold (please refer to Table 8).

Table 8.

Distribution of frequencies of different responses across different sensory profile of visual modality.

Responses (frequency)	High threshold	Low threshold	Percentage	Total	Chi square
Approach	129	11	58.33	140	97.54
Withdrawal	13	38	21.25	51
Neutral	19	30	20.42	49
Total	161	79	100	240	Significant p < 0.05

A significant association also exists between the sensory profile of the children and their response repertoire; more frequent approach behaviour being evident for children belonging to a high threshold sensory profile (please refer to Table 9).

Table 9.

Distribution of frequencies of different responses across different sensory profile of auditory modality

Responses (frequency)	High threshold	Low threshold	percentage	Total	Chi square
Approach	100	33	55.42	133	66.07
Withdrawal	6	21	11.25	27
Neutral	18	62	33.33	80
Total	124	116	100	240	Significant p < 0.05

Discussion

Discussion of pilot study

The ‘pilot study’ tried to examine if the paradigm of ‘visual selective attention’ or ‘visual paired comparison’ procedure developed by Fantz (1964) hitherto used to analyse ‘recognition memory’ in infants, can be effectively used in determining if children with LFA can differentiate between two stimulus of variable intensity and if such perceptual judgement is identifiable in behaviour.

As these individuals mostly do not use language to display their perceptual processing or ability to discriminate between two stimuli, it was necessary to find out alternative means of gaining access to these unobservable yet innate processes.

Originally devised to study perceptual processes in infant chimpanzees; Fantz (1958) found out that on being presented with pairs of stimuli varying in attributes such as color, form and size in a controlled environment, the infant chimpanzees demonstrated strong preferences for certain stimuli across testing sessions. For example, the colour blue was consistently preferred to red and a checkerboard pattern was preferred over a solid square image. These findings were interpreted as the first empirical demonstration of visual responsiveness, form perception and basic discrimination in an infant primate shortly after birth. Subsequently, on applying the same principle to human infants (Fantz 1964), the researchers noted that if a stimulus is presented repeatedly, then the extent of visual attention towards the stimulus decreases progressively over the trials. This phenomenon can be interpreted as an indication that the stimulus under consideration is becoming familiar or being remembered; i.e. a rudimentary substrate of memory is being created.

The results of the ‘pilot study’ make it quite evident that the overt behaviours of LFA reflect that they have been able to discern the difference between sensory stimuli of varying attributes (e.g. intensity). Akin to the infant participants of the studies quoted above (Fantz 1964; Fagan 1970), the participants of our study could not speak or indulge in meaningful verbal communication. But their overt behaviour clearly indicated their ‘preference’/‘interest’ or proclivity to attend to a novel stimulus. As both novelty and familiarity preferences are indices of categorization, it is fair to assume that the individuals with autism were discriminating the visual and auditory stimuli on the basis of their attributes.

The psychological significance of a stimulus in activating attention can be said to be acquired through learning wherein the organism understands that the stimulus is the signal of a mental or motor activity or because it predicts the introduction of an already significant event (Maltzman 1987; Wingard and Maltzman 1980). Thus, an ability to detect a variation in stimulus property in terms of intensity, quality, motion etc. can be reliably said to reflect an organism’s covert intellectual potential to learn the association between two stimuli or events in terms of their novelty, predictability and or significance to the context

General discussion

The findings of the present study provide direct evidence that direction and magnitude (as measured in terms of frequency) of ‘preference’ patterns towards stimulus can be considered as a measure of the LFA’s ability to distinguish between varying attributes of a stimulus.

The results reveal that there is a significant association between

• the frequency (p < 0.01) particular response pattern displayed towards a stimulus of higher intensity in the visual modality

• the frequency (p < 0.01) particular response pattern displayed towards a stimulus of lower intensity in the visual modality

• the frequency (p < 0.01) particular response pattern displayed towards a stimulus of higher intensity in the visual modality

• the frequency (p < 0.01) particular response pattern displayed towards a stimulus of lower intensity in the visual modality

In other words, the children with LFA consistently showed increased frequency of ‘approach’ behaviour towards the stimulus with high intensity across both auditory and visual modality.

It is further established from the findings that the response/preferences of the LFA to varying stimuli attributes are statistically significantly associated (p < 0.05) and functionally tied with the sensory profile of the same participants. The results can be construed as follows:

Threshold	Behavioural response
	Acting accordance to threshold	Acting to counteract threshold
High threshold (Less sensitive)	Poor/low registration	Sensation seeking
Low threshold (More sensitive)	Sensitivity	Sensation avoiding

Psychologists for the last 100 years have concurred on the proposition that intelligence and simple sensory discriminations are constrained by common neural processes, predicting a close link between them. Much before the development of the first intelligence test, Spearman had suggested that differential sensory discrimination abilities might be related to differences in human’s higher cognitive faculties (Deary,1994). Galton (1883) was of the opinion that exceptionally subtle sensory discrimination occurred in people with high cognitive ability.

The interplay between sensory discrimination and higher cognitive functions such as ‘attentional control’ can be also understood from the perspective—‘one can attend to the items in the focus of attention with a high or low degree of vividness…’ (Desimone and Duncan 1995; Reynolds et al. 2000); which, in turn, is a key substrate for enhancement of goal directed behaviours in a perceptually complex environment. According to Tsukahara et al. (2020), intelligence is associated with the ability to make fine sensory discriminations. In two large-scale structural equation-modelling studies, these investigators examined whether individual differences in attention control abilities can explain the relationship between sensory discrimination and intelligence. These authors replicated the finding that attention control fully mediated the relationships of intelligence/working-memory capacity to sensory discrimination and further showed that attention control plays a prominent role in relating sensory discrimination to higher-order cognitive abilities.

Hence, it is reasonable to infer that if a reliable index of sensory discrimination ability of children with LFA can be identified, it can be used to surmise about their cognitive ability; more explicitly a nonverbal measure of explicit or declarative memory. Past research using the VPC paradigm in human adults (Manns et al. 2000; Pascalis et al. 2005) dealt with memory dysfunction associated with structural damage in the brain; also suggesting that outcome of VPC research can be used to interpret the conjecture of memory.

One of the key strengths of the present study was inclusion of a test for measuring the sensory sensitivities of the children with LFA. Sensory processing difficulties are typical of ASD's which causes difficulty in the organization and regulation of sensory inputs. Kenet (2011) had opined that early sensory processing dysfunction has a significant impact on higher cognitive functions. Hence, hypo or hyper reactivity to sensory inputs will definitely have an impact on the child’s ability to differentiate between stimuli on the basis of their intensity.

Conclusion

This study provides a preliminary evidence for the construct that measuring sensory discrimination can be an effective way of measuring intellectual ability in children with LFA. There is a dearth of research literature involving LFA and to the best of our knowledge, few studies have attempted to address the issue of testability in individuals with LFA. Hence, this study is unique in its predominant focus on children with LFA.

There is no denying the fact that cognitive assessment is as crucial for research as it is for framing intervention plans as well as understanding a clinical condition in totality. But, the utility of most cognitive assessment techniques end at positioning the individual vis a vis a normative population instead of trying to understand the processes involved while responding to the cognitive task. The study also highlights the need for developing a new system of enquiry and measurement of intellectual ability in individuals with LFA, that surpasses the inherent limitation of conventional assessment tools.

It is a matter of concern that during the auditory sensory discrimination task, it was often difficult for the researcher to discern whether the LFA children were actually discriminating between the stimuli of differing intensity or whether the low intensity stimulus was often imperceptible to them. This observation is substantiated by the fact that LFA children with either sensory profile displayed more frequent ‘neutral’ responses when exposed to the auditory paradigm. It is pertinent to suggest at this juncture that more sophisticated assessment tools such as those capable of measuring covert responses like ‘fixation of eye gaze’, ‘pupillary dilation’ and ‘event related potentials’ etc., which can reliably reflect an individual’s information processing that goes on covertly and inaccessible to verbal interaction.

Funding Statement

This study is an original research done under the aegis of University Grants Commission (UGC) Special Assistance Program (SAP) Phase I allotted to the Department of Psychology, University of Calcutta. The fund from UGC SAP is distributed among a few eligible researchers/faculty of the department for individual research.

Disclosure statement

There is no conflict of interest.