In general, the limits imposed by working memory can be overcome by the use of more time-consuming strategies. Therefore, although performance might improve if working memory were larger, it might also improve if subjects simply thought more.
Baron, Thinking and Deciding
I think that all this time, human beings have been watched by creatures whose perceptions and understanding have been so far in advance of anything we have been able to accept, because of our vanity, that we would be appalled if we were able to know, would be humiliated. We have been living with them as blundering, blind, callous, cruel murderers and torturers, and they have watched and known us. And this is the reason we refuse to acknowledge the intelligence of the creatures that surround us: the shock to our amour propre would be too much, the judgement we would have to make on ourselves too horrible: it is exactly the same process that can make someone go on and on committing a crime, or a cruelty, knowing it: the stopping and having to see what has been done would be too painful, one cannot face it.
-- Doris Lessing, Memoirs of a Survivor
It’s a bit unclear without the context, but what he means is that subjects should think more about the task and realize that they need to, e.g. use a pen and paper.