week's Tech Tent seeks answers to all of these questions.

Nissan's new Leaf

Every week seems to bring more news of the move to electric motoring with many of the headlines centring on Tesla. Its Model 3 has been touted as the Model T Ford of the electric era, bringing an affordable battery-powered car to the mass market.

But maybe a traditional car company could be better placed to do that. The Nissan Leaf has been neck and neck with Tesla's Model S as the world's best-selling electric car - and this week the Japanese company unveiled a major upgrade to the car, giving it a much improved range.

Mind you, just how far it will go is somewhat unclear because there are a number of different methods of measuring that. The Japanese method gives it a range of 400km (250 miles), the European one reckons it will go for 230 miles, while the American system says it will go 150 miles before you need to plug it in.

Nikki Gordon Bloomfield, who does a weekly podcast about electric vehicles and was at the Tokyo launch, reckons the American range calculation is the most realistic. That is some way short of the Tesla Model 3's 220-mile range, but she says Nissan won't be too worried: "Nissan is not Tesla, nor does it want to be - it's selling a car for mainstream buyers."

She says that while there is some impressive technology in the Leaf there is nothing too flashy which might scare off those mainstream buyers, who are the target market as opposed to the early adopters who drool over the Tesla's futuristic features.

But there is certainly plenty of room for both companies. Electric car sales are surging, up 38% in Europe in the first quarter of 2017. But they still represent just 2% of all cars sold.

What's in a face?

Facial recognition is a technology that has come a long way in recent years. It is used in mobile phones as a means of secure login, at borders to automate the checking of passports, and by various law enforcement agencies to spot suspects or previous offenders.

But it's also very controversial - here in Britain there was an outcry over its use at the recent annual Notting Hill carnival, with accusations that it amounted to a form of racial profiling.

Tom Standage of the Economist, which has a special report this week on facial recognition, says computers are now much better than we are at recognising faces, one of a number of areas where feeding vast amounts of data into machines enables them to surpass human capabilities.

But a new study by Stanford University scientists shows how the technology could pose privacy dilemmas. The researchers showed a computer about 14,000 photos taken from an online dating site where the subjects identified themselves as gay or straight. It was then able to determine, with a greater accuracy than a human who was gay or straight, just by examining photos.

But, as Mr Standage points out, even if the algorithm appears pretty accurate when examining dating site photos, where people present themselves in a certain way, in other circumstances it will turn up plenty of false positives. Then how would we feel about its use in a country with repressive attitudes towards homosexuality?

Facts don't matter online

There's a well-known cartoon featuring a woman asking a man when he's coming to bed who then says: "I can't - someone is wrong on the internet." It sums up just how we can be drawn into arguments online with people who seem to be immune to reason.

But a neuroscientist at University College London says we are probably wasting our time if we think facts will change people's minds. Tali Sharot has written a book called The Influential Mind about how the methods we use in argument don't work because they don't fit with the way the mind operates.

She says the sheer volume of information now available on the internet is actually making things worse: "You can find information that supports anything you want to - and people do." So if you believe the world is flat or that vaccines cause autism, you can find material online to back up your beliefs.

"What we need to realise is fighting the confirmation bias is not very helpful," says Dr Sharot. "We can't change millions of years of evolution - our brains work in a certain way."

It seems a counsel of despair for anyone who believes that facts matter. But there is a cunning way of getting people to change their minds.

Dr Sharot points to a group of scientists who took a different approach when trying to convince parents that vaccines were not linked to autism. Instead of confronting them head on with studies that showed there was no link, they accepted the parents' beliefs and instead talked to them about the good things vaccines did - such as keeping children safe from measles or mumps.

"They highlighted something everyone agreed on," she says. This approach proved far more effective at changing minds than just a bald laying out of facts.

And do not feel smug in the belief that you are far too smart to be dogmatic about your beliefs even when you are shown evidence to the contrary. Dr Sharot says the research shows that the more intelligent you are, the more likely you are to have a confirmation bias.