Letters

Ability of toddlers to recognise TV images

BMJ 2000; 321 doi: https://doi.org/10.1136/bmj.321.7257.385 (Published 05 August 2000) Cite this as: BMJ 2000;321:385

Clinical utility of this milestone is not established

  1. Michael Hunter, specialist registrar in psychiatry (mhunter{at}doctors.org.uk)
  1. Community Health Sheffield NHS Trust, Northlands Community Mental Health Centre, Sheffield S5 8BE
  2. Royal Free Hospital, London NW3 2QG
  3. Basildon Hospital, Basildon, Essex SS16 5NL

    EDITOR—Lloyd and Brodie propose that the ability of an 18 month old child to recognise television images may be a useful milestone in the assessment of development.1 Their data derive from the examination of two conditions only: Down's syndrome and normality. To extend the concept to include learning disabilities in general, language disorders, and autism is not necessarily valid.

    The authors found that their milestone had a high degree of specificity (96%): very few normal children were unable to recognise television images. The sensitivity of the milestone—its ability to detect Down's syndrome—was 81%. One fifth of children with Down's syndrome were not detected. We do not know how sensitive the milestone is to learning disability generally, language disorders, or autism. We cannot assume that the findings with the group of children with Down's syndrome can be generalised. Therefore, the clinical utility of this developmental milestone has not yet been established.

    References

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    Authors' reply

    1. Ben Lloyd, consultant paediatrician (blloyd{at}rfc.ucl.ac.uk),
    2. Kanthini Brodie, consultant community paediatrician
    1. Community Health Sheffield NHS Trust, Northlands Community Mental Health Centre, Sheffield S5 8BE
    2. Royal Free Hospital, London NW3 2QG
    3. Basildon Hospital, Basildon, Essex SS16 5NL

      EDITOR—Hunter is quite right: our study says nothing about the proportion of children with various developmental problems who can recognise television images at the age of 18 months (apart from those with Down's syndrome).1 To answer this question properly would be a challenging task.

      Hunter's criticism applies equally to nearly all other tests of development. One exception is the checklist for autism in toddlers.2 Data concerning the sensitivity of this checklist are in press (Baron-Cohen, personal communication). The checklist comprises three items and was originally investigated as a possible screening test—hence the need to establish sensitivity. We know of no studies of an individual milestone in which the authors have reported the sensitivity of the milestone in relation to the identification of children with developmental problems.

      A child's development is evaluated by assessing the child's abilities on a range of tasks and behaviours. As with any milestone, passing our milestone does not mean that the child does not have a developmental problem. Similarly, failing our milestone does not mean that the child does have a developmental problem. The value of assessing a wide range of tasks and behaviours is that this process strengthens the conclusions that can be drawn about a child's developmental abilities. Our milestone is underpinned by a lot more data about how well normal children perform than is the case for many milestones that are used regularly. We stand by our conclusion that our milestone is a useful addition to the tasks and behaviours that can be used to assess the development of children aged between 15 and 24 months.

      References

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