The possibility screen time during early childhood could cause poorer attention later in a child's life is a major concern for both parents and researchers.
Earlier studies have suggested links between preschoolers' screen time and difficulties with attention.
But there is by no means consensus among the research community that such a relationship exists, and there have been conflicting results.
Two studies based on data from the Growing Up in New Zealand (GUiNZ) longitudinal cohort study may shed some new light on the issue, in the context of interactive media on offer for young children today.
The first study examined whether exceeding two hours of screen time per day for children aged two and almost four predicted symptoms of inattention and hyperactivity at four and a half years.
We used the Goodman's Strengths and Difficulties questionnaire to measure symptoms and found no association between higher levels of screen time and more symptoms.
A second study investigated the correlation between screen time and symptoms of inattention or hyperactivity for children at the age of four and a half.
Here, screen time and symptoms were measured at the same point in time, in contrast to the longitudinal approach of the first study. We found a significant association between more symptoms and higher levels of screen time.
These two findings suggest there is no causal link between screen time and symptoms of inattention and hyperactivity. But instead, parents of children displaying more of these symptoms may allow more screen time.
Potential explanations for longer screen time
Several factors may be at play, and one is the child's preference. Most children enjoy screen time. For children with Attention Deficit and Hyperactivity Disorder (ADHD), for instance, peer interactions are often difficult, and screen time may provide a more enjoyable and less stressful alternative.
Children with attention problems could find it hard to concentrate for long periods on pastimes such as reading a book.
Screen time, with its bright colours and action, may capture their attention and keep them interested.
Children with symptoms of inattention or hyperactivity are typically very active and impulsive and parents may find screen time can help settle and occupy their child for a while. It can also be something that parents and children enjoy doing together.
Much of the past research into the potential effects of screen time on children's attention has found associations between higher levels of screen time and poorer attention or other symptoms of ADHD.
Our findings don't imply these past findings have been incorrect, as most of this research has focused on television. The media landscape preschool children engage with today has changed considerably.
Newer screen technologies have been introduced and, arguably, a higher quality of screen time is now possible. For instance, one researcher argues that the features of modern touchscreen devices allow children to interact with them in ways similar to traditional toys, providing children with some of the benefits of traditional play when engaging with digital devices.
Our findings highlight the importance of considering the changing nature of children's screen time in future research into the potential effects on children's development.
It is important to remember our results do not rule out the possibility that very high levels of screen time or certain types of screen time could have immediate effects on children's attentional functions. Nor do our results suggest consistently high levels of screen time are harmless.
On the basis of my research, I advise parents to use their judgement about how much screen time is appropriate for their child, and how much may be excessive.
The children in our sample were preschool children (aged 2-4.5). Ministry of Health guidelines recommend less than an hour of screen time per day for this age group.
We think this is about right for children this young.
However, in COVID times, when parents are being parents, teachers and employees all at once, it's understandable that they may sometimes allow their children more screen time.
Our results may be reassuring to parents because they suggest that if preschool children end up having more than two hours of screen time per day while under COVID restrictions, this will not lead to long-term attention problems or ADHD.
Maria Corkin is a PhD candidate at the University of Auckland.