For example, consider the hypothetical case of a 54-year-old surgeon who, having read that playing videogames is helpful to maintaining dexterity for surgeons10, buys a games console and attempts to purchase a downloadable game from an online store via the console.
This transaction stands out in stark relief from the surgeon's customary spending patterns and far outside her demographic profile. Therefore, the bank immediately freezes her card and requires further authentication that the transaction is genuine, perhaps via a live phone call or a smartphone-based authentication system.
After this, the surgeon downloads her game, and all is well. In future, she can probably buy more videogames from the online store without further interruptions.
But in what ways might a machine learning system interpret this event, in terms of protecting the surgeon in future?
In the most cautious scenario, the model could add 'Buys PlayStation Games Online' to its understanding of the client's spending behavior. This may trigger additional freezes if the surgeon buys a game on any other platform, further impeding the customer experience. It's a granular solution that covers the incident but doesn't advance the model's flexibility, insight or autonomy.
- Minor demographic extension
Alternately, the AI might characterize the customer as more generally interested in video games and permit a slightly wider range of related purchases. Though this increases the attack area, it's a small increase and an acceptable and informed compromise between customer experience and customer security.
- Large demographic extension
What happens if the model is comparing the surgeon to typical histories within her age/status demographic? Having seen a number of people across a historical customer base pay off their mortgages, empty their nests, and indulge in a little mid-life atavism, the AI may begin to expect further such 'indulgent' purchases that are more strongly associated with a younger age-group and socio-economic status. This could make the AI more permissive in terms of allowing deviation from previous behavior, for instance with purchases traditionally associated with a younger age group. In such an eventuality, the attack surface is notably increased.
- Baseline becomes renormalized
In the case of a very poorly-configured model, this unexpected incursion from the 18-24 demographic into the 50-64 age range could cause a reassessment of the baseline expectations of the model, which will now flag purchases by the customer that are typical of her demographic.
- Anomalies become acceptable
By contrast, a less sophisticated model could deduce that the customer has become 'unpredictable', and begin to 'expect the unexpected' from her — probably the most disastrous result in terms of protecting her in the future.
Since these are all technically valid approaches to automated model revision, and since many other types of feedback-driven risk assessment models are susceptible to this kind of rogue logic, it's not difficult to understand the current cautious attitude to model validation and explainability in AI deployments for financial services.