Thomas Sutcliffe: TV research needs health warnings

It is one of the most elementary tenets of scientific research that a well-designed experiment should only contain one variable. if you're testing for the effect of a particular substance you have to be sure that its presence or absence is the only thing that changes between tests. This is particularly important when you're testing humans, those multi-channel receivers of stimuli, obvious and subliminal.

it's no good testing a tranquilliser and having a happy, smiley set of lab technicians administer the real thing while surly, sour-faced assistants chuck the placebos at the subjects because you won't be able to tell what's responsible for your results. And this fact can make things very tricky when the presence of the substance you're testing is inextricably bound up with the absence of a different but equally potent substance. How do you devise an experiment which will tell you whether the effects you record are the result of something that's there or something that's missing?

I hope Ofcom will give some serious attention to this conundrum as they prepare to review the effect of television aimed at very young children, apparently in response to recent French research which found that television watching undermined the development of pre-school children, encouraging passivity and delaying language acquisition. As a result Ofcom's French counterparts now insist that cable programmes for young viewers must carry a health warning pointing out that television can slow the development of young children "even when it is aimed at them". The general implication was clear. Even responsibly made television is a kind of toxin, the administration of which must be carefully controlled and monitored. And you can find the same underlying assumption that it is the application of television that is the problem (rather than the deprivation of something else) in much American research. in 2007, for example, the official journal of the American Academy of Pediatrics published a paper linking early childhood television viewing to attention problems in adolescence – the essential burden of which was that television acted as a debilitating pollutant of early childhood.

The problem was controls. That particular study controlled for "gender, attention problems in early childhood, cognitive ability at five years of age, and childhood socioeconomic status". But I can't see how they could have controlled for what must have accompanied excessive television watching in early years, which was the accompanying neglect or indifference of adults. That's the problem in a nutshell. High rates of television viewing in very young children is almost invariably a measure of the absence of something else – stimulating adult interaction – and in crudely identifying television as the origin of later problems you could easily mistake a symptom for a cause. Television needn't necessarily be blameless, of course. in letting parents off the hook (or getting them off the hook, as virtually every exhausted parent must have felt at times), television might carry some blame. But the idea that the Teletubbies radiate some neurologically stunting beams, quite independent of parental decisions about how their children are nourished and nurtured, would still be wrong. And social actions taken on the basis of that incomplete information could easily be worse than silly.

The assumption that children won't watch as much television if thoughtfully made children's programmes are rationed or restricted is, I would suggest, deliriously wishful thinking. They might just end up watching Jeremy Kyle – and live in a world where not even the box in the corner took an interest in how they might grow and develop.

There's a fine line between a gangster in fiction and in reality

It's not entirely surprising to read that several of the cast members of Gomorrah, above, Matteo Garrone's excellent film about the Camorra, have been charged in reality with the crimes they re-enacted in fiction. From Bugsy Siegel and George Raft on, the demarcation between being a gangster and successfully pretending to be one has been as ragged as a lifer's underpants. indeed there's a case for saying that the internet Movie Database might usefully add a "Criminal Convictions" tag to its entries for Mafia and gangland films.

While making his film – in some of Naples' most lawless neighbourhoods – Garrone also enjoyed the assistance and advice of Camorra wise guys, acting as the slum equivalent of those civic film boards that encourage directors to put their town on the map. Clearly they felt they had nothing to fear from authenticity, even though they are depicted as brutal thugs. They don't feel quite the same way about non-fiction though. Garrone's film was based on a book by the journalist Roberto Saviano, who now lives under permanent police protection; he named real names while Garrone substituted "types". See the film – it's gripping and takes you to bits of Naples you would only see if your sat nav failed. But spare a thought for the chronicler that the bad guys want to kill.

'A decent respect to opinions of mankind'

The current edition of Foreign Affairs contains a long job application – sorry, "position paper" – by Richard Holbrooke, outlining the unnerving to-do list for the next American president (1: Save planet, 2: Find substitute for foreign oil... etc). This includes the fact that Venezualan foreign aid to Latin American countries now exceeds US aid by a factor of five – a "hearts and minds" gap which should worry any administration. it also reminds its readers that – contrary to what you might imagine from the past eight years – open contempt for the attitudes of other governments isn't integral to the American way. Holbrooke quotes the Declaration of independence, which begins by explaining that it is motivated by "a decent respect to the opinions of mankind". in other words if you want to set up a shining city on a hill – rather than a well-defended gated community – you really have to take some care over how you look to others.

* I enjoyed hearing Paul Day defend his St Pancras frieze of a skeletal tube driver about to mow down a toppling passenger. "An image like this could have drawn the public to admire and respect that particular job," he said on the Today programme. I think he should now turn his skills to a commemorative plaque for the great crash of 2008, in which he could – with equal "sympathy" – portray bankers as flesh-eating zombies and hedge-fund analysts as pitchfork-wielding demons.