Academic journal article Canadian Journal of Experimental Psychology

Increased Attention to the Irrelevant Dimension Increases Interference in a Spatial Stroop Task

Academic journal article Canadian Journal of Experimental Psychology

Increased Attention to the Irrelevant Dimension Increases Interference in a Spatial Stroop Task

Article excerpt

Abstract In a spatial version of the Stroop task where subjects must attend to the position of a word and ignore the word itself, we argue that interference results because selective attention is only partially successful. If so, then increasing attention to the word should increase interference. Experiment 1 showed increased interference with position naming when subjects must be prepared to attend to either the word or its position. Experiment 2 required subjects to first name the position of the word and then later to recall which word had been presented. This resulted in increased interference with position naming when the word was followed at a short SOA by a pattern mask. Experiment 3 employed both word reading and position naming and showed that a large reverse Stroop effect occurred with both vocal and manual responses when subjects had to be prepared to attend to either dimension of the stimulus.

In a typical Stroop task, a word is presented to a subject and the subject is required either to read the word or to report some other attribute of the word, such as its colour or position. In the latter case, response times are strongly influenced by whether the word and the attribute to be reported are congruent or incongruent. For example, when subjects are asked to report whether the stimulus words left, right, above or below are located to the left, to the right, above or below a fixation point, responding is faster if the stimulus word and its position are congruent, and is slower if the stimulus word and its position differ (Seymour, 1973). On the other hand, if the word is to be named, the congruity or incongruity of the spatial attribute of the word has little effect on response time. The word naming situation has often been referred to as the reverse Stroop condition.

Interference effects in the Stroop task have frequently been attributed to a failure of selective attention in that subjects seem to be unable to avoid processing the stimulus word. Treisman (1969) has attributed this failure of attention to an inability to selectively attend to different dimensions of an object. On the other hand, there are data which indicate that Stroop interference may not simply reflect a breakdown of selective attention, because the amount of interference can be influenced by the way attention is deployed. Francolini and Egeth (1980) presented their subjects with a circular array containing a variable number of red and black items and asked them to report the number of red items. When the red items were digits which were inconsistent with the number of red items, reaction times were longer, but when the to-be-ignored black items were inconsistent digits, no interference was obtained. Kahneman and Henik (1981) presented their subjects with two words, one on either side of the fixation point. One of the words was printed in coloured ink and the other was printed in black. Subjects were instructed to ignore the black word and report the colour of the other word. When the non-black word was an incompatible colour word, the usual Stroop interference effects were obtained, but no interference was obtained when the to-be-ignored black word was an incompatible colour word. These studies indicate that when attention is directed elsewhere in the visual field, words or numbers are not automatically processed to the extent necessary to produce Stroop interference.

There is also evidence that subjects may be able to focus attention on one dimension of a stimulus object and ignore other dimensions. Harvey (1984, Experiment 4) presented a cue (X or x) followed by the words HI or LO in congruent or incongruent positions. The case of the cue indicated whether the subject was to report the position of the word or name it. The interstimulus interval (ISI) between the cue and the word varied from 50 to 950 ms. For both the position and word naming tasks, responses were slower on incongruent trials, but this effect declined with ISI. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.