Identifying Behavioral Bias in Wealth Management

Jackson is a high-net-worth individual who has been managing his own investment portfolio for over a decade. He prides himself on his analytical skills and often relies on his personal judgments to make investment decisions. Recently, Jackson attended a seminar on behavioral finance, where he learned about various cognitive biases that can affect investors' decision-making processes.

Despite this newfound awareness, Jackson finds himself falling into some traps, particularly when it comes to overconfidence in his abilities. He often disregards expert advice and sticks to his original investment thesis, even when presented with contradictory evidence. Jackson's financial advisor, Sarah, is concerned about how Jackson's biases may impact his long-term investment performance.

In assessing Jackson's behavioral tendencies, which of the following cognitive biases is likely the most significant factor impacting his investment decisions?