In this research, we examined the impact of icons' depth on user attention and search efficiency during icon recognition. First, 61 participants were asked to view an image composed of flat (2D) and neumorphic (3D) icons arranged in a circle, with their eye movements monitored by an eye tracker. Each participant was asked to watch the pictures carefully then complete four search tasks under the following four conditions (with suitable prompts) while viewing them: selecting a target 2D icon from among 2D icons, selecting a target 3D icon from among 3D icons, selecting a target 2D icon from among mixed 2D and 3D icons, and selecting a target 3D icon from among mixed 2D and 3D icons. The results indicated that 3D icons performed better in terms of attention distribution and attention attraction than 2D icons. There were no significant differences in terms of search time or accuracy between selecting a target 2D icon from among 2D icons and selecting a target 3D icon from among 3D icons, selecting a target 2D icon from among mixed 2D and 3D icons, and selecting a target 3D icon from among mixed 2D and 3D icons. The findings have practical significance for icon design and can provide guidance for designers, prompting them to either use 2D or 3D icons to achieve intentional visual and cognitive effects. •The depth information of icons affects users' visual attention significantly.•Neumorphic 3D icons are better in terms of attracting attention than 2D icons.•There was no significant difference in terms of search efficiency between 2D and neumorphic 3D icons.