Smarter

Can your mind truly become smarter? In Smarter: The New Science of Building Brain Power, Dan Hurley makes the case that intelligence, long seen as a fixed biological limit, can be developed through structured practice, lifestyle choices, and emerging interventions. He traces a revolution in cognitive science—from the discovery of brain plasticity to modern methods of training working memory, attention, and executive control. The result is a hopeful but evidence-grounded argument that intelligence is partly malleable, especially when you combine mental and physical approaches.

From fixed IQ to growth mindset

Early intelligence research assumed that IQ was like eye color—set by genetics and largely unchangeable. Hurley revisits this assumption through pivotal studies that challenged it, most famously Susanne Jaeggi and Martin Buschkuehl’s 2008 experiment showing that adaptive working-memory tasks, such as the dual N-back, could raise fluid intelligence scores in college students. This study, alongside Torkel Klingberg’s work in ADHD and Michael Merzenich’s plasticity experiments, marked a turning point: the realization that practice can reshape not only skills but underlying cognitive capacity.

Intelligence as a system of trainable components

Hurley defines intelligence as a set of interlocking systems—working memory, attention control, reasoning, and learning efficiency. Each system can be stretched within biological limits, much like muscle fibers respond to resistance training. Cognitive neuroscience confirms that practice alters neural connectivity, especially in prefrontal and parietal regions linked to executive function. Over time, this translates to improved reasoning and learning capacity, whether in children, adults, or patients recovering from brain injuries.

A wider landscape of interventions

Hurley’s narrative doesn’t stop at brain games. He expands to diet, exercise, music, meditation, and even technology and pharmacology. Physical exercise—documented in Arthur Kramer’s and Teresa Liu-Ambrose’s trials—improves executive function and protects against cognitive decline. Music lessons strengthen working memory and attention networks, while mindfulness meditation (Yi-Yuan Tang and Michael Posner) increases white-matter efficiency in the anterior cingulate cortex. Together, these findings form a mosaic of modifiable influences on cognition.

Evidence and controversy

The book also maps the scientific debate. Psychologist Randy Engle points out that many training claims are overstated, distinguishing near-transfer (improvement on similar tasks) from far-transfer (gains in unrelated reasoning). Hurley balances optimism with skepticism, noting over 70 randomized, placebo-controlled studies showing cognitive training benefits but also acknowledging null results when designs are weak. His pragmatic conclusion: intelligence can shift modestly but meaningfully under rigorous, adaptive conditions.

Real-world implications and ethics

Because intelligence influences nearly every life outcome—from school success to income and health—the possibility of improvement carries profound social and ethical weight. Hurley addresses how cognitive enhancement intersects with education, equity, and medical ethics, using Down syndrome research and prenatal testing as examples. He urges policies that expand access to safe, evidence-based interventions while guarding against over-commercialization and social bias.

Your takeaway

The book’s ultimate message is actionable: intelligence arises from genetics and experience, but it can be nurtured through challenge, adaptivity, and persistence. Combining exercise, mindfulness, targeted cognitive tasks, and healthy environments may not make you a genius—but can make your brain measurably more effective. Hurley reframes intelligence from destiny to potential, urging you to treat your mind as a trainable system rather than a static score.

Hurley places working memory—the mental workspace for holding and manipulating information—at the core of trainable intelligence. He contrasts short-term memory’s passive storage with working memory’s active processing capabilities, describing how adaptive training can strengthen this vital skill. The dual N-back, now famous as a research tool, forces you to track two simultaneous streams (sound and visual patterns) while constantly updating comparisons. The challenge recruits prefrontal circuits, triggering neural efficiency gains detected by fMRI studies from John Jonides and colleagues.

The rule of adaptivity

Adaptivity—tasks that become harder as you improve—is the critical principle. Klingberg and Merzenich both demonstrated that keeping training at the threshold of your ability produces durable neural change. Jaeggi and Buschkuehl used such adaptive regimens and found dose-dependent results: students who trained longer displayed greater increases in reasoning performance. The dosage principle parallels physical fitness: short, frequent, progressively difficult sessions yield the best outcomes.

Neural efficiency and transfer

fMRI results show reduced activation after training—evidence of increased efficiency rather than strain. Strengthening the connectivity between lateral prefrontal and parietal regions appears to improve fluid reasoning. While some critics argue that gains are task-specific, Hurley reminds you that “narrow” improvements in working memory underpin broader reasoning under many test conditions.

How to train effectively

Hurley’s recipe echoes expert consensus: engage in short (20–30 minute) adaptive sessions several times per week, expect frustration early, maintain motivation, and measure progress realistically. Like strength training, cognitive growth depends on repetition and difficulty, not gimmicks. The idea is not to play easy games but to challenge your mental limits continually.

Beyond direct brain games, Hurley explores how everyday choices influence cognition from infancy to old age. Nutrition, sleep, exercise, and environmental safety form the bedrock of brain potential. He highlights breastfeeding benefits, the dangers of toxins like lead, and the limited impact of most supplements. Your primary mission is harm prevention and holistic care rather than miracle nutrients.

Exercise as a mental catalyst

Aerobic and resistance training emerge as the most reliable non-cognitive ways to boost brain performance. Kramer’s landmark walking study in older adults and Liu-Ambrose’s resistance trials both showed measurable improvements in executive function. Children’s exercise programs correlate with larger hippocampal volume and better attention. Hurley likens exercise to “mental fertilizer”—it increases neurogenesis and maintains flexible cognitive networks throughout life.

Diet and early-life influences

Hurley debunks nutritional hype: omega-3 and B-complex supplements rarely yield consistent cognitive gains outside of clinical deficiencies. However, early sustenance and stability matter deeply—famine, neglect, and abuse cause measurable declines. Prevention and balanced living far outperform pills.

Learning, music, and meditation

Music training strengthens auditory discrimination and attention networks, while mindfulness meditation revamps neural efficiency within weeks. Tracey Shors’ research supports combining physical exercise (to create new neurons) with effortful learning (to help them survive), forming synergistic pathways for durable cognitive improvement.

Hurley integrates Seth Grant’s evolutionary insights to explain how genes set conditions for plasticity rather than fix limits. Two rounds of genome duplication in vertebrate ancestors created redundant gene copies that diversified into specialized functions—especially the Dlg/DLG gene family controlling synaptic scaffolding. These duplications gave evolution raw material to build complex neural systems capable of learning and adaptive control.

No single gene for intelligence

Grant’s work underscores why intelligence arises from many interacting genes, each contributing small effects. Human mutations in DLG2 mirror attention deficits found in mice—a striking cross-species sign of functional conservation. Hurley notes that while genes constrain possible ranges of performance, experience sculpts expression inside those ranges.

Plasticity connects biology and learning

Neural circuits remain malleable long after development. Just as duplicated genes explored new functions over millennia, your neurons can update synaptic strength in response to practice. Genetic predisposition defines potential, but plasticity—expressed through training and experience—determines outcome. Understanding this interplay reframes intelligence as evolution’s experiment in adaptability, not a binary gift.

Hurley doesn’t shy from the scientific clash between optimism and rigor. Researchers disagree on whether training effects genuinely transfer beyond practiced tasks. Randy Engle emerges as the field’s conscience, insisting that working memory and fluid intelligence are correlated but not identical. The dispute hinges on method: how controls are designed, how long training lasts, and who volunteers.

Understanding transfer and controls

Studies that use passive controls often overstate benefits. Active controls—tasks equally engaging but theoretically neutral—reveal modest or null results when conditions are too easy or short. Hurley teaches you to distinguish near, moderate, and far transfer and to weigh study quality before drawing conclusions. Meta-analyses show consistent near-transfer but contested far-transfer to general reasoning; long training durations (like Lindenberger’s COGITO experiment) increase reliability.

Reading science with caution

The takeaway is balance: training can strengthen specific mental capacities but not instantly raise global IQ. Combined approaches, active engagement, and motivation yield the best chance for tangible cognitive improvement. Hurley invites you to read every claim with methodological curiosity rather than naïve enthusiasm.

Hurley ultimately looks forward to multimodal strategies—the interplay between physical fitness, digital training, attention practices, and emerging neuroscience tools. Combining modalities amplifies outcomes more reliably than any single method. Exercise increases brain volume; working-memory training sharpens reasoning; meditation stabilizes attention; and technology provides optional enhancement under ethical supervision.

Synergistic interventions

Arthur Kramer’s trials and Louis Matzel’s mice show that exercise plus cognitive practice produces superadditive gains. Tang’s mindfulness regimens improve focus; Schellenberg’s music lessons enhance verbal intelligence. These complement each other. tDCS (transcranial direct-current stimulation) and memantine appear capable of boosting training effects modestly, though Hurley warns against unsupervised use.

Ethical and social horizons

From Down syndrome therapy debates to military cognitive-program funding, enhancement invites moral reflection. Hurley asks you to weigh benefits against identity, fairness, and equal access. Intelligence improvement should expand human opportunity, not reinforce inequality.

Vision for the future

The future Hurley envisions is integrative: intelligence enhancement through combined behavioral, biological, and technological methods under ethical guidance. His pragmatic hope is not for superhuman intellects but for widespread improvement in learning, attention, and emotional regulation—making human brains more adaptable and humane.