The brain training industry generated over $3 billion in revenue in 2020, selling the promise that playing cognitively demanding games will make you smarter. Luminosity, BrainHQ, Cogmed, and dozens of competitors offer programmes claiming to boost memory, attention, and general cognitive ability. Meanwhile, neuroscientists and psychologists have spent years rigorously testing whether these claims hold up. The consensus is more nuanced — and more instructive — than either the marketing or the sceptics suggest.
The Dual N-Back Controversy
The most scientifically discussed cognitive training paradigm is the dual n-back task, which requires participants to simultaneously track two streams of stimuli (typically visual positions and auditory letters) and identify when each stimulus matches the one that appeared n steps earlier. The task is demanding, engaging, and improvable with practice. In a 2008 study, Jaeggi, Buschkuehl, Jonides, and Perrig reported that training on the dual n-back task produced gains in fluid intelligence on transfer tests — the first credible claim that a mental exercise could improve g itself, not just specific task performance.
The study was hugely influential and triggered a wave of replications. The results have been decidedly mixed. Some replications found similar transfer effects; many did not. A 2014 meta-analysis by Melby-Lervåg and Hulme examined 23 studies of working memory training and found robust near-transfer effects — participants improved on working memory tasks similar to those they trained on — but near-zero far-transfer effects on fluid intelligence, reading comprehension, or arithmetic. The training benefits did not generalise to meaningful cognitive skills beyond the trained domain.
The Transfer Problem
The core challenge in cognitive training research is the distinction between near transfer (improving on tasks closely similar to the trained activity) and far transfer (improving on broad cognitive abilities like fluid intelligence, executive function, or real-world academic and occupational performance). Near transfer is easy to achieve and largely unsurprising — practice improves performance. Far transfer, to genuinely broader cognitive capacity, has proven extraordinarily difficult to demonstrate convincingly.
A 2014 consensus statement signed by 75 cognitive scientists and neuroscientists noted that "the scientific literature does not support strong claims that brain-training programs improve, or will improve, general cognitive ability." This reflects not a finding that the brain cannot change, but that targeted computerised training has not been shown to produce the kind of broad generalisation that constitutes genuine cognitive enhancement.
What Actually Works
The evidence is more encouraging when we look beyond commercial brain training to lifestyle factors with strong neurobiological underpinnings. Aerobic exercise has the most consistent evidence base: multiple randomised controlled trials show that regular cardiovascular exercise increases BDNF (brain-derived neurotrophic factor), promotes hippocampal neurogenesis, and produces measurable improvements on working memory and executive function tests. Studies suggest effects comparable in magnitude to the claimed gains from intensive computerised training, with the added benefit of pervasive physical health co-benefits.
Quality sleep is perhaps the most underappreciated cognitive performance variable. Sleep deprivation studies reliably show that reducing sleep to six hours per night for two weeks produces cognitive performance deficits equivalent to two full nights of total sleep deprivation — and crucially, subjects dramatically underestimate how impaired they are. Adequate sleep (7-9 hours for adults) is essential for memory consolidation, prefrontal cortex function, and the type of associative thinking that underlies creative problem-solving. For many people, improving sleep quality may be the highest-return cognitive investment available.
Learning genuinely new and demanding skills — a new language, a musical instrument, complex programming — appears to produce broader cognitive benefits than targeted training tasks, likely because it engages a wider range of neural circuits and demands sustained, motivated engagement over months or years rather than brief computerised sessions.
Key Takeaway
The honest answer to "can you improve your IQ?" is: somewhat, through specific means, but not dramatically through commercial brain training. The most evidence-supported levers for optimising cognitive performance are regular aerobic exercise, prioritising adequate sleep, managing chronic stress, addressing nutritional deficiencies, and engaging in genuinely challenging new learning. These are not glamorous interventions — but the evidence for their cognitive impact is far stronger than for any app-based programme currently on the market.