Reaction to Eriksen & St. James (1986) by Richard Thripp
EXP 6506 Section 0002: Fall 2015 – UCF, Dr. Joseph Schmidt
September 24, 2015 [Week 5]
Eriksen and St. James (1986) believe their experiments support the zoom lens model, which differs from the spotlight model in that it proposes we can vary our attentional distribution on a continuum from a wide field of view to a fraction of a degree (pp. 226–227). The spotlight model typically involves a discrete or even binary dichotomy where we can only have a broadly or narrowly focused attentional field, but with restricted or nonexistent choices in between these two poles (p. 226).
As a photographer, I could not help but thinking of analogies to camera lenses and digital processing chips while reading this article, particularly since that is the crux of the authors’ analogy. The authors indicate in the discussion for experiment 1 that a 50 ms stimulus onset asynchrony (SOA) does not allow time for the attentional field to “zoom in,” so to speak, so an incompatible noise letter three positions away from the cued area delays the subject’s response time, but if given 100 ms, delayed reaction time is not observed, which may indicate the noise letter is now excluded or “cropped out,” so to speak (p. 233). This reminds me of the autofocus delay on cameras, which often measures in hundreds of milliseconds and can prevent the photographer from capturing desired moments.
Regarding the displays in experiment 1 where 3 of 8 letters were cued, reaction times paradoxically increased in the 200-ms SOA condition as compared to the 100 ms or even 50 ms displays. As an explanation, the authors present the possibility that with 3 of 8 letters cued, attending to the whole display may be nearly as efficient as attending to the cued area; thus, subjects may have elected to attend to the whole field in some displays, increasing reaction time (p. 234). Unfortunately, this is a post-hoc explanation and the experiments did not entail the collection of data to support this possibility. While the authors believe experiment 2 verified this explanation, it also had a very small sample size (n = 6), fewer trials, and an incompatible noise letter that was comparatively ineffective (p. 239). Fortunately, the authors seem to have produced a stronger argument that the cued letters are searched simultaneously rather than serially—specifically, that reaction times between 1, 2, and 3 cued positons increased far less than it should have if the positions were searched serially (p. 234).
In both experiments, multiple cued letters were always adjacent to each other in the circle. It would be interesting to see 2 cued locations not adjacent to each other—would the subject revert to processing the whole display, or somehow divide attention between the non-adjacent cued locations? How would this fit into the zoom lens model? Also: the authors assume that with no precues, all display elements are processed in parallel (pp. 232–233). In experiment 2, they include displays where all 8 letters are precued (p. 237). It would be nice to see if there are any implications of precueing all the positions versus none of them. When all the letters are underlined, does the underlining have any effects on reaction time? In neither experiment were there any conditions that had no cued or precued letters.
The authors’ ANOVA results have impressive statistical significance and they have purposely used methodology similar to past research in the hopes of allowing compatible comparisons (p. 229). However, I have lingering doubts about unspecified variables. We are given very little detail about the subjects—only that they are right-handed University of Illinois students who self-reported having normal or corrected vision (pp. 229, 237). Who is to say these self-reports were accurate? Why did the authors not bother with a visual acuity test? What were the ages of the participants? Did they have any other visual or attentional problems? The sample sizes of 8 and 6 are fairly small, meaning that a smaller number of non-equivalent participants could have thrown off the results. This research was published in 1986 and used a tachistoscope with individually constructed slides with affixed letters, rather than computer displays (pp. 229–230). The care and uniformity with which these slides were constructed is not specified. We are told subjects received reaction time feedback after each trial (p. 230), but not how this feedback was structured or conveyed. Whether the feedback was spoken by the researchers or conveyed in text or graphs may have implications. Further, encouraging participants to keep their error rate below 10% (p. 230) could have been a factor in the unusual reaction time pattern shown in figure 4 (p. 232)—perhaps this pattern is not indicative of parallel processing, but rather error avoidance? Despite the statistical power of their results, the authors may be overreaching, based on the assuredness of their conclusions.
Eriksen, C., & St. James, J. (1986). Visual attention within and around the field of focal attention: A zoom lens model. Perception & Psychophysics, 40(4), 225–240. doi:10.3758/BF03211502