The category effect in visual detection and partial report

Dixon, Peter

doi:10.3758/bf03207157

Cited by 9 publications

(18 citation statements)

References 40 publications

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“…On one hand, one may regard the result as an inherent part of the interference effect; that is, the interference effect consists of a tendency to make false alarms at short SOAs. This interpretation is supported by the robustness of this pattern of results: It was found in all five of the experiments reported by Dixon (1986), as well as in Dixon (1985), Dixon and Twilley (1988), and in some of the conditions of Briand and Klein (1988). On the other hand, one might regard the false alarm increase as a separate effect from the overall decrease in accuracy.…”

supporting

confidence: 59%

Perceptual information and response strategies: A comment on Briand and Klein.

Dixon¹

1988

Canadian Journal of Psychology / Revue canadienne de psychologi

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This framework is based on the target-array confusion model described by Dixon and distinguishes between the available perceptual information subjects have to make a response and the strategies subjects use to combine this information and arrive at a decision. It is assumed that variations in response strategy will affect primarily the relative number of misses and false alarms in this paradigm and will leave overall per cent correct largely unaffected. Instead, per cent correct will be primarily a function of the available perceptual information. RKSLIME Nous proposons un cadre de travail pour discuter Tcffet d'interference trouvc par Briand ct Klein (1988), Di Ix>llo et Moscovitch (1983), et Dixon (1986. Ce cadre de travail est base sur le modele de confusion cible-rangee d6crit par Dixon et fait la distinction entre ('information perceptuellc disponible a laquclle les sujets doivent rcpondre et les strategies que les sujets utilisent pour combiner ccttc information en vue d'arriver a une decision. Nous assumons que des variations dans la strategic de reponsc affecteront principalement le nombre d'erreurs ct dc fausses alarmes dans ce paradigme tout en laissant intact lc pourcentage global correct. Celuici sera principalement fonction de 1'information perceptuelle disponible.Recently, a number of researchers have reported an interference effect that occurs when subjects view a brief alphanumeric display followed by a single target item (Briand & Klein, 1988; Di Lollo & Moscovitch, 1983;Dixon, 1986; Dixon & Twillcy, 1988). Generally, it is found that subjects' ability to decide whether the target item was present in the array is poor when the target follows the array by 100-200 ms, but improves with either longer or shorter stimulus-onset asynchronies (SOAs). This pattern of performance is reminiscent of metacontrast masking, in that performance is a U-shaped function of SOA. However, as argued by Di Lollo and Moscovitch and by Dixon, the interference is unlikely to be due to the same kind of mechanism: The effect occurs over larger spatial and temporal intervals than has been reported for metacontrast and is unaffected by a variety of display parameters that are important in visual masking, such as the spacing of the array items or the distance between the array and the target. Instead, it has been proposed that the interference effect is due to some interaction between the array and the target at a more symbolic or conceptual level (Di Lollo & Moscovitch).Dixon (1986) reported an intriguing aspect of this interference effect: Generally, the errors that subjects make at short SOAs are false alarms, in which subjects claim *Preparation of this article was supported by Natural Sciences and Engineering Research Council of Canada Grant A8263. The author would like to thank h'red Morrison for comments on an earlier version. Address reprint requests to

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supporting

confidence: 59%

Perceptual information and response strategies: A comment on Briand and Klein.

Dixon¹

1988

Canadian Journal of Psychology / Revue canadienne de psychologi

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“…There was also an overall effect of SOA [F(2,22) = S2.%, p < .001], with accuracy declining as SOA increased. Previous research using this task has found a nonmonotonic effect of SOA, with accuracy being worst at SOAs of 100-200 msec and improving with longer SOAs (Di Lollo & Moscovitch, 1983;Dixon, 1985Dixon, , 1986. It is likely that such a trend would have been apparent in the present experiment as well if SOAs of 100 and 200 msec had been included.…”

Section: Methodsmentioning

confidence: 48%

“…If there was no difference between single-category displays and mixed-category displays, it would be strong evidence that the category effect was due to feature differences between letters and digits. Previous work with the category effect demonstrated that the effect is most likely to occur when there is only a single relevant item in the display (Dixon, 1985;Duncan, 1980Duncan, , 1983b. Consequently, in the mixed-eategory displays in this experiment there were six irrelevant category items (letters) and one relevant category item (a digit).…”

Section: Methodsmentioning

confidence: 95%

“…In the first experiment, the visual feature control used by Krueger (1984) was applied to the target-array task ofDi Lollo and Moscovitch (1983) and Dixon (1985). If there was no difference between single-category displays and mixed-category displays, it would be strong evidence that the category effect was due to feature differences between letters and digits.…”

Section: Methodsmentioning

confidence: 99%

“…When the target preceded the array, the task was essentially a visual detection task; when the target followed the array, the task resembled a partial-report task in which observers were cued on the basis of item identity (Townsend, 1973). Previous studies had found large and robust category effects in this task, both when the target followed the array and when it preceded the array (Di Lollo & Moscovitch, 1983; Dixon, 1985). The present study investigated whether this category effect still would occur when stringent controls were placed on visual feature differences between categories.…”

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confidence: 99%

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Conceptual and physical differences in the category effect

Dixon

Shedden

1987

Perception & Psychophysics

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In these experiments we tested whether physical differences between letters and digits could account for the category effect in visual detection and partial report. In our task, observers decided whether a target item matched any item in a briefly presented array. This yielded a visual detection task when the target preceded the array and a type of partial-report task when the target followed the array. In Experiment 1, the stimulus set consisted of nine digits and nine letters modified to match the digits on the basis of visual similarity. Partial-report performance was better in a mixed-category condition than in a single-category condition, but no such effect occurred in visual detection. However, the similarity of items between categories may have biased observers against using category information to perform the task. When the similarity was controlled both within and between categories in Experiment 2, a category effect emerged in visual detection as well. A third experiment, using a same-different reaction time task, verified that the stimuli were equally similar within and between categories. The results indicate that physical differences alone cannot explain the category effect.It has been found in a number of tasks that the visual processing of an alphanumeric display is more efficient when some of the items come from an irrelevant category. For instance, it takes less time to find a digit in an array of letters than in an array of other digits (e.g., Egeth, Jonides, & Wall, 1972), and detection of a digit in a brief display is more accurate when the distractors are letters rather than digits (e.g., Schneider & Shiffrin, 1977). This finding can be referred to as a category effect. The category effect is important in theories of visual information processing because it has suggested to some that, at some level, characters are processed in parallel with unlimited capacity (e.g., Duncan, 1980;Gardner, 1973). However, this conclusion has not been universally accepted, and the mechanism underlying the category effect remains controversial (Deutsch, 1977;Kahneman & Treisman, 1984;Krueger, 1984). In this study, we tested an often proposed counterexplanation of the category effect that can be termed the partial analysis account.The unlimited parallel processing view of the category effect assumes that the items in a visual display are identified and categorized in parallel without requiring effort or attention on the part of the observer. However, such subsequent operations as transferring items to short-term memory or comparing items may limit performance. In this view, the category effect occurs because information about the category of items in the visual display can be used to separate relevant from irrelevant items. For instance, if the observers in a visual detection task know This research was supported by Natural Sciences and Engineering Research Council of Canada Grant A8263 to the first author. We would like to thank Vince Di Lollo for comments on an earlier draft. Requests for reprints should be sen...

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On the nature of the span of apprehension

Dixon

Shedden

1993

Psychol. Res

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The category effect in visual detection and partial report

Cited by 9 publications

References 40 publications

Perceptual information and response strategies: A comment on Briand and Klein.

Perceptual information and response strategies: A comment on Briand and Klein.

Conceptual and physical differences in the category effect

On the nature of the span of apprehension

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