Children from the poorest families are losing out educationally by not having access to the internet or a car, new research has shown.
Those from the poorest families are almost a year behind average-income families in vocabulary tests when they start school at five, the Sutton Trust study said.
It found factors such as whether a child was read to daily or taken to the library influenced the gap.
But in a test in which children were asked to identify pictures, the largest single contributor to the gap between children from low-income and middle-income families was lack of internet access at home. Taken together with not having a car, these factors explained about 13 per cent of the 11-month gap.
Other material circumstances, such as not having a dishwasher or being unable to replace worn-out furniture, did not affect children's test scores, the study found.
The researchers said 62 per cent of people in the lowest income group - the equivalent of a family of four living on #163;9,800 per year after tax - had no internet access at home compared with 17 per cent of the middle-income group, who were living on #163;25,000 a year.
The report said parents hid the effects of social exclusion from small children, but added: "The picture of sharp inequalities will come to have greater consequences for low-income children as they age and attend school, when their more limited range of experience will come into sharper contrast with that of more affluent children."
The Government has recently announced it is spending #163;300 million on providing computers and broadband access to low-income families with children aged seven to 14.
Professor Jane Waldfogel, one of the report's authors, said: "The findings regarding internet access confirm that there are substantial income-related gaps in computer ownership and internet access, and that these factors matter for children's school achievement.
"So the Government is definitely on the right track in ensuring computer and internet access for low- income families with school-age children. Our findings suggest they could go even further and provide such access to families with younger children."
Bernadette Duffy, head of the Thomas Coram children's centre in central London, said the benefits were clear: "People may use the internet to go on to Mumsnet and say they have problems getting their child off to sleep and ask for suggestions. This works because not only do they get easy access to different strategies, but they also realise it is not just them 'getting it wrong'."
Parenting behaviour, when taken as a group of factors, had the largest impact, explaining about one-fifth - or two months - of the gap between low and middle-income families.