“…The visibility of the Wrst stimulus (the test stimulus) is then impaired by the second stimulus (the mask). This impairment can be a reduction of the perceived brightness (e.g., Alpern, 1953;Blanc-Garin, 1966;Fry, 1934;Growney, Weisstein, & Cox, 1977;Piéron, 1935), an increased threshold for the test stimulus (e.g., Cox & Dember, 1970;Kolers, 1962;Lefton & Orr, 1975), its reduced discriminability (e.g., Bernstein, Proctor, Proctor, & Schurman, 1973;Breitmeyer, Love, & Wepman, 1974;Weisstein & Haber, 1965) or identiWability (e.g., Dember, Bryant, & Chambers, 1975;McKeever & Suberi, 1974;Mewhort, Hearty, & Powell, 1978;Schurman, 1972) or simply that it has phenomenally disappeared (e.g., Burchard & Lawson, 1973;Kolers & Rosner, 1960;Mayzner, Tresselt, & Helfer, 1967;Toch, 1956;Werner, 1935).…”