The flaw of psychology (as a science) - and a reason many people refer to social science as fake science - is a lack of falsifiability.
For a scientific test to be falsifiable you must be able to prove it false.
Karl Popper, the philosopher of science famous for advocating falsifiability, used the example of the black swan - "All swans are white" is falsifiable because you can observe that black swans exist.
Businesses use these psychological theories on sales pages, in marketing campaigns, executive coaching seminars, strategic positioning and more. So the doers (business) are using theories by theorists (social scientists) to grow faster, be better, get smarter.
This isn't an efficient use of resources.
Over 10 years doing marketing for my own companies (plus much larger ones) I've noticed one overriding disparity between what happens in real life and what the theorists tell us.
People don't do what they say they'll do.
At the coalface, on the practioners side of the world, you see this every day. So I use the heuristic to only pay attention to what people do, not what they say.
Humans lie. We don't mean to. We don't even realise we're doing it. But we're natural storytelling creatures. And the stories we tell to ourselves are often stronger than the reality that is around us.
We say we buy the expensive beer. But really we buy the cheap stuff.
There's a growing trend of user research being done, mostly by tech companies, where they invite several people into an entirely manufactured environment to test prototypes of product ideas and get feedback from these (paid) testers.
That is not smart. This is not real. It is the result of the type of unfalsifiable, bulls**t that has passed from the theoretical, non-doers, in social sciences to the practical doers in business.
The feedback from these fake users is about as useful as asking Donald Trump to not lie during his next speech.
What they "think" is not relevant. What they "say" is not relevant. They're not real customers. They're not spending their own money, worse, they're being paid to give feedback. They're giving you fake feedback within a fake environment that is significantly more linear and comfortable than the real world - where money issues, crying children, angry bosses or partners, bad weather, family emergencies cause tension that contribute to the real feedback we need from customers.
So what is the solution?
The only feedback that matters is that from real paying customers after you've shipped a product or feature. What they say matters. It matters because they used their own money to buy it. It matters because they want the best from the product and will be critical about it. It matters because they aren't getting paid to use the product. It matters because in the real world they might be having a shitty day so you get harsh feedback you can use to quickly improve the product.
Before that, you're just making educated guesses.
Which means you don't waste time and money on months of what-ifs, expensive (and unessecery) consultants, wasted meetings, wireframes and money spent on user research.
Instead, you ship.
You ship fast and get feedback on the fly. Test, measure and learn from real people in the real world and watch how quickly you make progress.