Reptile Brain vs Thoughtful Brain
Build systems that override your investing reflexes.
Coffin frames investor behaviour as a fight between two systems: the reactionary 'reptile brain' that responds to flashy stories and gut feelings, and the slower, thoughtful brain that reasons critically. The reptile brain wins by default, especially when content algorithms are tuned to its triggers.
The framework's job is to put structures around decisions so the slow brain reliably makes the call. Habits, advisor relationships, and pre-committed rules act as guardrails because inspiration is too unreliable to drive long-term investing.
It also explains why advisors add value beyond stock-picking: a chunk of their fee buys behavioural enforcement during volatile markets and major life decisions.
- Defaults beat willpower; build them before stress arrives.
- Habits compound where inspiration evaporates.
- Sensationalist content is engineered to trigger the reptile brain.
- Outsource behavioural enforcement when self-discipline is the constraint.
- Slow-brain decisions need to be made before the fast-brain situation appears.
- Identify your reptile triggersNote which formats, creators, or events historically push you to act — crisis videos, big single-day moves, hot-keyword tickers. Awareness is the first guardrail.
- Pre-commit your rulesWrite rules for contributions, rebalancing, and selling before you encounter the next shock. Make them specific enough to execute without re-deciding under stress.Pro tipSchedule contributions on autopilot so they don't depend on how you feel.
- Install habits in place of inspirationBuild a daily or weekly review routine — read a quarterly report, check filings, log decisions. Habits keep the slow brain on the field.WarningDon't conflate doing the routine with making good decisions; review the outputs too.
- Curate your content dietReduce exposure to sensationalist formats, especially during volatile periods. Rebalance toward concept-teaching creators rather than stock-pick channels.
- Outsource behaviour where neededIf self-discipline keeps failing, hire an advisor or use a robo-advisor for the structural part of the portfolio so the reptile brain has less surface area to attack.
His top-performing video for 2023 was about Silicon Valley Bank, illustrating how crisis content gets traction. Even responsibly framed, the format taps the reptile brain.
He notes that one of advisors' biggest values is enforcing habits and managing behaviour during tough markets and spending choices, not just picking investments.
Coffin draws on the dual-process language popularised in behavioural finance and his own work as a portfolio manager. He's seen advisors' biggest contribution to clients during tough markets be behavioural rather than analytical — reining in reactions and keeping people invested.