Reducing　the　＂intention-behavior　gap＂　in　pro-environmental　purchasing　decisions　is　crucial　for　environmental　protection.　This　study　aimed　to　explore　how　natural　sounds　influence　the　＂intention-behavior　gap＂　in　proenvironmental　purchasing　decisions　by　employing　a　laboratory　experiment　focused　on　physiological　responses.　Specifically,　it　investigated　the　effects　of　natural　sounds　(e.g.,　birdsong)　and　unnatural　sounds　(e.g.,　factory　noise)　on　individuals　with　high　levels　of　environmental　movement　activism,　focusing　on　their　proenvironmental　purchasing　decisions　and　physiological　attention　mechanisms.　The　results　showed　that　compared　to　unnatural　sounds,　individuals　with　high　environmental　movement　activism　significantly　increased　their　green　product　purchase　rates　when　exposed　to　natural　sounds.　Compared　to　unnatural　sounds,　they　exhibited　lower　heart　rates　and　higher　beta　band　activity　in　the　right　prefrontal　cortex　when　viewing　green　product　information　under　natural　sounds.　Additionally,　the　difference　in　heart　rate　between　natural　and　unnatural　sounds,　significantly　predicted　the　difference　in　green　products　purchase　rate.　Within　the　environmental　psychology　framework,　the　findings　suggest　a　novel　connection　between　Attention　Restoration　Theory　and　the　evolutionary-constructivist　perspective,　demonstrating　that　natural　sounds　enhance　top-down　attention　toward　green　products　in　individuals　with　high　levels　of　environmental　movement　activism.　This　effect　may　relate　to　a　reduction　in　the　＂intention-behavior　gap.＂　This　study　provides　valuable　insights　into　biophilic　design　principles　for　designing　and　testing　environmental　settings　that　promote　pro-environmental　purchasing　decisions　through　natural　sounds.