Defining the StanDarD ObServer in the 1920s two researchers from the uK, david wright and john guild, performed color matching experiments using human volunteers to develop and quantify the color ability of a standard, or average, human observer. in 1931 the Cie published the 2° standard observer based on their research. this standard observer is called 2° because, during the color matching experiment, subjects looked through a hole that allowed them a 2° field of view. At the time it was believed that all the color-sensing cones of the eye were located within a 2° arc of the fovea, located directly back from the retina of the eye. the experiments were performed by projecting colors from across the visible spectrum onto a screen. multiple people matched each spectral color light using a combination of red, green, and blue lights. the curves generated from this data resulted in bar x, bar y and bar z functions, referred to as the 1932 Cie 2° degree standard observer.