The internet is full of claims about color psychology: "red creates urgency," "blue builds trust," "green means go." Some of these have a kernel of truth. Most are oversimplified to the point of being misleading.
What the Research Says
The strongest finding is not about specific colors. It is about contrast and distinctiveness. A CTA button that stands out from its surroundings gets more clicks than one that blends in, regardless of whether it is red, green, or orange. This is called the isolation effect or Von Restorff effect.
This means the relationship between your CTA color and its background matters more than the CTA color itself. A red button on a red-themed page performs poorly. The same red button on a blue-themed page performs well because it stands out.
Cultural Context Matters
Color associations are culturally specific. White symbolizes purity in Western cultures and mourning in many East Asian cultures. Red means danger in the West and prosperity in China. Any universal claims about color psychology should be treated skeptically.
Practical Implications for Palette Design
When building a conversion-focused palette, focus on three things. First, ensure your CTA color has maximum contrast against its typical background. Second, use color temperature contrast: if your page is predominantly cool, make your CTA warm. Third, use your Supporting colors for secondary actions, creating a clear visual hierarchy.
The best CTA color is not red or green. It is the one that is most different from everything around it.