'Exner and Charpentier have pointed out that the peripheral retina is more sensitive to flicker than the central' (33)

'Charpentier [note: 'Archives d'Opthalmologie, 1890.'] has found the duration [of stimulus reqired to induce light sensation] less for retinal points corresponding with the peripheral part than for those corresponding with the central part of the field of vision.' (35)

'In 1885, Marey's associate Adolph-Moïse Bloch adapted a version of the intermittently-obscured lamps that William Henry Fox Talbot and Simon von Stampfer had developed during the 1830s to physiological investigation. Where Talbot sought to measure light intensity itself, Bloch sought to establish a law regarding the rates at which individual sensation-flashes produced a continuous light-sensation under different conditions (Bloch 1885, 493-495; Schickore 2006, 254-255). Such studies prompted a range of physiological investigations into Stampfer's "stroboscopic" effects during the 1890s (e.g. Charpentier 1890; Schenck 1896; Marbe 1898).' (454)