Visual noise causes tunnel vision

Abstract

d isp lays s howe d 22 li ne s of le tt e rs co ns is t ing of al toget her 374 le tt e rs co ver ing the who le d isp la y area . Th e se c ond ma in var iab le was the width subte nded by the row 0/ re cognition st i muli . In th e Three Lett er d isplays , the thre e rec og nit ion le tte rs we re cl os e together, s l ight ly spread or wide ly scattered. In bo th No ise d isp lays, these matched let t er s we re s imilarl y d istribu t ed. Wit h vi ewing distances of 28 and 56 in, the three recogn ition width s subtended 1, 3 and 5 degrees , or 2, 6 and 10 deg rees re spect ively. Only the 1 or 2 degree presentation s we re en t ire ly foveal · the other widt hs requ ired pe ripheral and fov e al dis cr iminat ion .' Th e I~tters wer e 0.25 in hi gh and 0 .5 in between centers: they we re of h igh contrast on 8 .5 x 11 in whi te backgrounds . Fcch of the nine arrangements of displays and w idths was prepared in two d ifferent versi ons -w ith the three recognition le tters as N or C. The resu lting 18 cards were randomly mixed w ith an equal number of catch d isplays which had either no matching letters at a ll or only one mat ch ing letter to one side of the centra l letter . Figure 1 shows that the extra unwanted letters or visual noise gave the main effec t . Virtually perfect s cores were made with the Three Letter (No No i s e) at all widths of recognition display. But the additi on of unwanted letters to these identical patterns of three wanted letters gav e a ca tast r ophic reduction in recognition scores. These No i sec 0 n d i t ion s were harmful either as Line or a s Page displays. The worst imp airment was found when the recognition letters ' stretched into the per i p h er a Ire t in a. These Noise displays subtending 3 to 10 degrees aver aged only 10 per cent cor r ec t . Foveal recognition was a lso , however, definitely impair ed by peripheral visual noise , even when the three matching letters were adjacent to each other. Recognition s cores for material in the fovea fell to three-quarters or two-thirds of ac hieveme nt at the Results and Disc uss io n AbstractSs had qui ckly to detect similar ities between two upperca se letters presented peripherally and one other cent ral letter falling on the fovea. Thes e three cha r acters were so legible that this task was very easy when the three letters were flashed on by themselves. But the additi on of extra letters to this display seriously imp aired performance. The periphery of the retina could no longer accuratel y detect a t a glance whether items were similar. Fove al performance was also affected to some extent by extra items in the periphery of the retina. IntroductionPeople usually select the information they want from a general background of unwanted material. Pattern recognition often involves per ipher al matching in the sense that comparisons a r e mad e between one foveal item and many others pl aced in the periphery. Alternatively, similarities and differences a r e noted between two or more entirely peripheral items. This process...

Investigating the visual span in comparative search: the effects of task difficulty and divided attention

“…This result points out the possibility that previous reports on the effects of foveal load on visual span size (e.g. Crundall et al, 1999;Ikeda & Takeuchi, 1975;Mackworth, 1965;Williams, 1985Williams, , 1988Williams, , 1989 may actually re¯ect at least in part the effects of divided attention.…”

“…Crundall, Underwood, & Chapman, 1999;Ikeda & Takeuchi, 1975;Mackworth, 1965;Williams, 1985Williams, , 1989see Williams, 1988, for a review). Such studies typically employed two concurrent visual tasks, one of them involving the presentation of stimuli in the center of the display, the other involving the presentation of stimuli in the periphery.…”

“…In some of these studies (e.g. Mackworth, 1965;Williams, 1985Williams, , 1989, investigators found this decline in performance to be greater for targets at larger eccentricities, arguing that the foveal load reduced the useful ®eld of view (i.e. the visual span).…”

Spatiotemporal Segregation in Visual Search: Evidence From Parietal Lesions.

“…The contraction of space found in Experiment 6 is reminiscent of what in the applied and fundamental research literature has become known as tunnel vision: the phenomenon that the functional (or useful) field of view shrinks under conditions of cognitive and attentional load (Chan & Courtney, 1993;Holmes, Cohen, Haith, & Morrison, 1977;Ikeda & Takeuchi, 1975;Kahneman, Beatty, & Pollack, 1967;Leibowitz & Appelle, 1969;Mackworth, 1965;Miura, 1990;Plainis, Murray, & Chauhan, 2001;Rantanen & Goldberg, 1999;Sanders, 1970;Webster & Haslerud, 1964;Williams, 1982Williams, , 1988Williams, , 1995cf. Lavie & Tsal, 1994).…”

Global attributes in visual word recognition: Contour perception of three-letter strings

“…For 3 out of 4 situations, contour xxk shows an LVF advantage, while contours xxx and xkx show RVF advantages; (b) (o-i): Mackworth (1965) found a foveally oriented scanning in letter strings.…”