A friend tells me that well-meaning people often ask her what the special talent of her son with autism is. She tends to answers: “Gabriel’s special talent is having a meltdown in the supermarket because the flicker of the fluorescent lights bothers him so much.” The question my friend is asked is born of the Rain Man effect; fiction and the media are full of cases of art/maths/music savants with autism. But such coverage of autism doesn’t help my friend much. In the supermarket she’s still the recipient of disapproving looks when Gabriel, now 11, is screaming on the floor.

The Germanwings tragedy has brought mental health on to the front pages. More attention on the impact of mental illnesses is warranted; far less is spent on care of these than of physical conditions. However, it also highlights the tendency for myths and rare but salient incidents to colour public perception in unhelpful ways.

People with developmental disabilities and their families are disadvantaged socially (divorce rates and isolation are high) and economically (family income is significantly lower). Society’s attitudes to disability and to mental illness are critical to their quality of life and we have a long way to go.

Last Thursday, we celebrated World Autism Awareness Day. The National Autistic Society, the first parent group to be founded for autism anywhere in the world, raises money for schools, respite services, adult homes and tries to improve understanding of this still puzzling condition. Around the world, autism charities do the same for the 1% of children and adults with an autism spectrum disorder.

It is interesting that the National Autistic Society receives only a fraction of the charity donations given to heart disease or cancer charities. At first sight, this is surprising; the public stereotype is of a beautiful, distant-eyed child with autism, unable to interact with those around him. Surely such a stereotype should be an appealing object of charity? However, the sad truth is that our charity strays only so far from home. We give most generously to charities that we imagine might one day help us. We could all get cancer or heart disease in the future, but unless you have a relative with autism, it is unlikely to be something you worry about.

Empathy is an interesting thing. We may think we “neurotypicals” are socially skilled, but in fact our empathy is limited by many factors. Work by cognitive neuroscientists Professor Tania Singer at the Max Planck Institute in Liepzig and Dr Geoff Bird of the Institute of Psychiatry at King’s College London shows us that our empathy for someone is critically affected by how much we identify with them. For someone within our “in group” our hearts may bleed, but for someone perceived as part of an “out group” we can be amazingly callous. Religious and ethnic wars around the world illustrate this.

The danger is that those with developmental disability, mental illness or other stigmatised conditions are unconsciously seen as alien, different from us. The lack of empathy that results was horribly evident in the Winterbourne View care home case. More generally, we all turn our backs in situations where our help could make a difference when we allow other people to become just “other”.

Neurocognitive research on empathy tells us something else interesting about the conditions for caring. Singer’s research shows that people have less empathy for the pain of those they perceive as having transgressed or cheated in a simple game. This, too, has importance for understanding our attitudes to mental illness. Unlike comparably severe physical illness, we often explicitly or implicitly blame those with mental illness: “How selfish to put her family through that”; “If they stopped her disability benefits, I wonder how long she’d stay agoraphobic!” Perhaps these judgments also explain our lack of empathy for those with mental illness.

Our risk assessments around mental illness are also completely wrong. Despite the high-profile reporting of tragic acts of violence by those with mental illness, the statistics clearly show that people with schizophrenia, bipolar disorder, depression or other mental illnesses or disabilities are far, far more likely to be the victims than the perpetrators of crime.

Rationally, we have nothing to fear from people with mental illness. They, by contrast, have plenty to fear from us. Improving our understanding of, and empathy for, those with mental illness and developmental disorders starts with better knowledge and communication and a leap of imagination to put ourselves in their shoes.

This is perhaps hardest for the most vilified groups, but it is important to recognise that those who, for example, harm children have themselves typically been harmed, as children. If we could see the wounded child when we look at the culpable adult, we might be more compassionate without condoning the crime. And we might invest more, emotionally and as a society, in the care of the most vulnerable.

Shouldn’t social work be a high-prestige, highly paid profession, given its importance? How could we make that happen? How hard will that be while the media only report failures and never reflect successful intervention and care?

Returning to autism, the first generation of children diagnosed with autism are now growing old and many people are coming to autism clinics for first diagnosis in their 50s or even 70s. Yet we know scarcely anything about autism in old age; the vast majority of research money is spent on children with autism. This too reflects, perhaps, the limits of our “neurotypical” imagination and compassion. It is easy to feel for a child, less so for an adult, especially an older adult. Old people with mental illness or any disability are doubly stigmatised and especially vulnerable.

For a more compassionate society, we need radically to rethink our attitudes to mental illness and developmental disabilities; not us and them, but all of us together.

Francesca Happé is professor of cognitive neuroscience at the Institute of Psychiatry, Psychology & Neuroscience, King’s College London