Reader Comments

Post a new comment on this article

SWIFT moves its eyes across whatever it is presented with

Posted by Potsdam_EM_Group on 28 Sep 2007 at 22:15 GMT

Ever since the discovery that reading consists of a series of fixations rather than a continuous sweep of the eyes across the text [45], investigators have looked to the eye movements for clues into how reading works. E-Z Reader [46] and SWIFT [47] model the eye movements of reading. These models include a word-recognition stage whose latency is affected by language properties such as word familiarity and word length, so they do make some use of context and word shape, but they cannot read at all when the letter information is knocked out.

Pelli and Tillman write that their results present challenges for models of eye-movement control during reading, like SWIFT and E-Z Reader. This is certainly true but a few qualifications of the sweeping conclusions appear to be in order. First, SWIFT can read sentences in which letters are replaced with "z", that is with letter information being knocked out completely. This condition is referred to as mindless reading (Rayner & Fisher, 1996; Nuthmann, Engbert, & Kliegl, 2007; Vitu et al., 1995). As recently, reported by Nuthmann and Engbert (2007) the model is able to recover quite a few of the characteristics of subjects whose eye movements are measured during such a task. The reason is that SWIFT contains an autonomous timer for saccade generation. In other words, lexical processing is not a necessary condition for saccade generation. Interestingly, S, W, L processes map approximately on predictability, word length, and word frequency, respectively. In this sense, the present article addresses at a conceptual level exactly the three independent variables that feature prominently in reading models. Consequently, the dissociations may help to constrain their future implementations. Research in this direction may lead to an implementation of word recognition that is in line with theoretical developments in this field (see Reichle et al., 2003).

Nuthmann, A. & Engbert, R. (2007). Evaluation of the SWIFT model using z-string scanning as an oculomotor control condition to normal reading. Journal of Eye Movement Research, 1, M3-06.
Nuthmann, A., Engbert, R., & Kliegl, R. (2007). The IOVP effect in mindless reading: Experiment and modeling. Vision Research, 47, 990-1002.
Rayner, K., & Fischer, M. H. (1996). Mindless reading revisited: Eye movements during reading and scanning are different. Perception & Psychophysics, 58, 734–747.
Reichle, E. D., Rayner, K., & Pollatsek, A. (2003). The E–Z Reader model of eye-movement control in reading: Comparisons to other models. Behavioral and Brain Sciences, 26, 445–526.
Vitu, F., O’Regan, J. K., Inhoff, A. W., & Topolski, R. (1995). Mindless reading: Eye movement characteristics are similar in scanning strings and reading text. Perception & Psychophysics, 57, 352–364.

RE: SWIFT moves its eyes across whatever it is presented with

DenisPelli replied to Potsdam_EM_Group on 26 Oct 2007 at 16:54 GMT

Thank you. That's interesting.

Denis Pelli & Katharine Tillman