Tuesday March 2 2010
Do toddlers' learning DVDs do more harm than good?
Parents who buy educational DVDs to give their toddlers a head start may be doing more harm than good,” the Daily Mail reported. It said a study on a DVD from Disney's Baby Einstein series found it did nothing to boost vocabulary and children who started on the DVDs at a younger age actually had a worse vocabulary.
The main aim of this study was to look at the effects of the learning DVD Baby Wordsworth on children’s learning of 30 specific words. The DVD was found to have no effect on the children's learning of the words, or on general language ability.
A separate analysis examined how DVD viewing before the study affected children’s general language ability. This found that those who first watched Baby Einstein DVDs at earlier ages had poorer language. However, some caution should be applied here, as only 37 children were assessed, other factors may have influenced the results, and multiple tests were carried out, thereby increasing the likelihood the results are due to chance.
Parents should not be concerned that they are harming their children by encouraging them to watch educational DVDs as part of a variety of interactive learning activities. At the same time, these findings suggest that some word learning DVDs may have limited effect on toddlers’ vocabulary development, at least in the short term.
Where did the story come from?
This research was carried out by Dr Rebekah A Richert and colleagues from the University of California. The study was funded by the National Science Foundation and the paper was published in the peer-reviewed medical journal Archives of Pediatrics & Adolescent Medicine.
This research was reported in The Daily Telegraph, Daily Mail and Daily Express. The newspaper headlines all focus on the possibility that the learning DVDs could do more harm than good. These news sources did not highlight the limitations to the finding that starting to watch DVDs earlier in life may have a detrimental effect on language skills.
What kind of research was this?
This randomised controlled trial (RCT) investigated the effect of a DVD aimed at improved word learning in young children. The study also included some cohort analyses looking for relationships between previous DVD watching and general language abilities.
An RCT is the best design for looking at whether an intervention has an effect. This is because randomisation is the best way to obtain well-balanced groups, where the only difference between the groups should be the intervention being investigated (in this case the DVD). In addition, having a control group means that researchers can observe what would happen over time even without the intervention. Even though nested within an RCT, the cohort analyses looking at DVD watching prior to the study could be affected by confounding.
What did the research involve?
The researchers enrolled 96 children of one to two years of age and their parents. The children were randomly assigned into two groups: one group watched an infant learning DVD at home over a six-week period, and the other group did not. The researchers then compared the children’s vocabulary development to see if watching the DVD had had any effect.
The DVD used in the study was Baby Wordsworth, from the Disney Baby Einstein series. The DVD is 35 minutes long and focuses on 30 words for objects and rooms around the home. It uses puppet displays, live footage, pictures, sign language, text and speech to convey these words. The DVD group was asked to let their children watch the DVD five times every two weeks, but otherwise follow their normal routine.
Children and parents from both groups attended the research laboratory for assessments at the start of the study and every two weeks thereafter. The children’s development was assessed at the first assessment using a standard scale (the Bayley Scales of Infant and Toddler Development-III, BSID-III). Parents also answered a series of questions on their children’s exposure to DVDs in general, and also specifically to Baby Einstein DVDs.
At each visit, parents reported which of the 30 words in the DVD their child understood, and which they could say. Children were shown paired pictures of objects from the DVD, and asked to point to the picture showing a target word.
At the end of the study, all children and parents watched the Baby Wordsworth DVD together, and researchers noted how often parents and children used the 30 words highlighted in the DVD. A sub-group of 37 parents also completed an assessment of their child’s word abilities using the MacArthur Communicative Development Inventory (CDI).
The researchers were looking at whether the age at which a child first started watching DVDs (prior to the study) affected their language abilities (on the CDI) and development. They also looked at how the children’s language abilities with the 30 target words changed over the six weeks of the randomised controlled part of the study, and whether this differed between groups. Finally, they looked at how often parents and children used the 30 target words in the final DVD-watching session, and whether this differed between the groups. These analyses took into account the children’s ages.
What were the basic results?
At the start of the study there were no differences between the two groups of children in their development (BSID-III) score. This score was not significantly related to parents’ reports of how often their children had previously watched DVDs, including the Baby Einstein DVDs.
Overall, the DVD and no-DVD groups had similar language abilities according to the CDI measure at the end of the study. The CDI scores were not significantly predicted by how often children watched DVDs in general or Baby Einstein DVDs specifically, or the age at which they first watched a DVD prior to the study. However, CDI scores could be predicted by the age at which a child first watched a Baby Einstein DVD specifically, with children who started at an earlier age having lower CDI scores. However, this relationship only reached borderline statistical significance (p=0.05).
Both the DVD and the no-DVD groups improved in their understanding and ability to say the 30 target words at the end of six weeks. There were no significant differences between the DVD and the no-DVD group in words understood, words said, or picture identification.
In the final joint DVD session, parents of younger children in the DVD group said more of the target words to their children. In this session, younger children from both groups were unlikely to say the target words, while older children were more likely to say the target words if they had been in the no-DVD group and were watching the DVD for the first time.
How did the researchers interpret the results?
The researchers concluded that there was no evidence that children learned target words highlighted in a DVD aimed at teaching them these words. They also say that DVD exposure was not related to general language learning “providing no evidence that exposure to this DVD over six weeks either helped or hindered children’s general language learning”. They suggest that more research is needed to “examine whether infant-directed media are effective in teaching infants and toddlers”.
This research suggests that the word learning DVD assessed here had no effect on toddlers’ language abilities over a six-week period. There are points that are important to note:
- Caution needs to be applied to the finding that the age at which a child first watched the Baby Einstein DVDs was related to general language ability. Only 37 children were included in this assessment, and multiple statistical tests were carried out, meaning that differences are more likely to have arisen by chance. Also, there was no overall relationship between general language ability and the children’s age when they first watched a DVD, or the frequency of watching any DVDs or the Baby Einstein DVDs in particular. These findings need to be confirmed in further, larger and preferably prospective analyses.
- The analysis looking at DVD watching prior to the randomised controlled part of the study was essentially a cohort analysis and, as such, may be affected by other differences between the groups other than the age at which children started to watch Baby Einstein DVDs. It is also possible that parents may not have accurately remembered the age at which their children first started watching DVDs, or how frequently they watched them.
- The study tested one DVD, Baby Wordsworth, in toddlers over a six-week period. It is not clear whether similar results would be obtained for other DVDs, or what the longer-term effects would be. Results may not apply to older children.
Parents should not be concerned that their children are being harmed by watching learning DVDs. However, this study suggests that at least some DVDs may have limited effect on toddlers’ vocabulary development in the short term.