In an era where privacy has been steadily eroded, the one sanctuary that most of us have held on to is the privacy of the thoughts within our heads.

But it seems even this last redoubt might soon come under siege. Because while for centuries now psychics have claimed the ability to read minds, now we are making this capability real, thanks to rapid development in the field of neurotechnology, and specifically, the creation of brain computer interface (BCI) devices.

But once more it seems the pace at which we can develop new capabilities is going to outstrip our ability to consider and manage the consequences.

So what is a BCI? Put simply, it is a device for sensing and interpreting the signals of the brain. Where common neurotechnology devices such as MRI scanners can determine what parts of the brain are active at any given time, a BCI device can determine what the brain is actually doing – or more specifically – what it is thinking.

The detail and accuracy of BCI devices is astounding – down to the level of individuals words. A trial of a BCI device in 2021 on a person who was paralysed and non-verbal saw them use an implanted BCI device to communicate at a rate of 18 words per minute at 94 per cent accuracy. While the techniques used suggest there is still some want to go to true mind-reading (this example focused on imagined muscle control), this is another step along a seemingly inevitable pathway.

Today the capabilities of BCI devices greatly depends on the proximity they can achieve to the neurons they are trying to sense, with the best results achieved using implanted devices where electrodes are inserted under the skull, such as in the example described above. Good results have also been achieved from devices implanted under the scalp, and even wearable (non-invasive) devices are showing promise.

Exactly how accurate these wearable devices will prove remains to be seen, but given their use is mostly unregulated (especially as they are not ‘medical’devices), there is a good chance that a lot of investment dollars will be keen to see how finely their resolution can be tuned (Elon Musk certainly seems keen).

But the implications of BCI technology go far beyond giving speech to the speechless. Creating a devise that enables one party access to the thoughts or another has massive implications across many aspects of life.

Take marketing for example. Not only might a marketer be able to see through the difference between what a person thinks and what they say, but they could also be able to pick up on signals and make suggestions based on thoughts that a person might not even be aware of. This would be a much more accurate form of contextual advertising, based on evidence rather than inference.

Whether any individual might be willing to submit to constant mind surveillance by their favourite brand is unlikely – although with the right incentive, not impossible. However, there is one scenario where BCIs are likely to play a major role – the metaverse.

One of the key barriers to truly immersive virtual reality experiences is the control interface, which must use hand and body gestures as proxies to control actions within the virtual world. Using a BCI however means a person might only have to think about ‘running’ in a specific direction, or about picking up an object, or any manner of other interactions, for that thought to be translated into an action in the virtual world.

How much of a stretch is it to go from monitoring a participant’s commands to interpreting all of the other data that the BCI is extracting?

One immediate application is contextual advertising, and the ability to present a brand at the precise moment when a person is thinking about that product category.

For content platforms, whose job is to keep people engaged, the BCI can be used to present content which has been determined as being most likely to garner a response at that moment in time. Given the furore that erupted when Facebook was shown to be manipulating people’s moods through the content it showed them, it is not hard to see the possible harm that might result.

Or what about for an online casino, which now knows exactly what it needs to offer to keep a player engaged and spending?

While none of these possibilities are viable with the BCI technology available today, at the current rate of progress, this decade is the one where the boundaries will be tested – not some distant and unforeseeable future.

So what will the world look like when not even the thoughts in our head are ours alone?

If you’re interested in learning more about the technical, legal, and ethical challenges of neurotechnology, then please come along to the second Neurotechnology Forum, taking place in Sydney on May 17.