2.5.1Overview
In the previous studies, stereotyping effects were examined by a dual task paradigm to investigate the effects on a primary task (impression formation and memory performance) whilst simultaneously performing a secondary task (working memory load) which is presumed to use the same cognitive resources as the primary task (Baddeley, 1986, 1996). However, besides phonological and central executive load, cognitive load of the visual sketchpad is also discussed in cognitive psychology literature (e.g., Alvarez & Cavanagh, 2004; Baddeley, 1986; Baddeley &
Andrade, 2000; Kruley et al., 1994; Logie, 1986; Seitz & Schumann-Hengsteler, 2000; Sims &
Hegarty, 1997; Vandierendonck, Kemps, Fastame, & Szmalec, 2004).
The visuospatial sketchpad is a workspace in which an image can be stored and manipulated to guide future behavior (Baddeley, 2003b). As social information is very often visually encoded, capacity demands on social memory is a field that deserves closer attention. Social cognition research has neglected the influence of visual load on social memory. Until now no study (literature review February, 2008: PsycINFO, PsycARTICLES) has investigated the influence of visual load on long-term memory of stereotype-inconsistent and stereotype-consistent information that is not presented in terms of verbal information (read or heard), but instead in terms of pictures. In order to fill this gap, the present study investigated the effects of visual load on long-term memory of stereotype-consistent and stereotype-inconsistent information.
Participants were asked to take part in a study about memory processes. For this purpose, they were presented objects used in everyday life that were either consistent with the stereotype of the elderly or inconsistent, that is, consistent with the stereotype of young men. Participants were randomly assigned to either a no visual load or a visual load condition. Previous studies (Kruley et al., 1994; Phillips & Christie, 1977) have found that “retaining a spatial array of dots uses the working memory resources of the visuospatial sketchpad” (Sims & Hegarty, 1997, p. 323). Thus, this paradigm was adopted using a 5 ¯ 5 matrix in which five points were randomly distributed.
For blocking the visuospatial sketchpad, participants had to memorize the arrangement of the dots until they were asked for recognition of the grid. The cognitive load was supposed to disrupt encoding of the stereotype-relevant objects presented as pictures, thus leading to worse long-term memory of stereotype-inconsistent information.
It was hypothesized that memorizing visual objects relies on the storage and processing functions of the visuospatial sketchpad. Therefore, it was expected to find more impairment when
the matrix memory task was paired with objects memorization task than when the memorization task was presented alone. In the no load condition, the incongruency effect (for meta-analytic reviews, see Rojahn & Pettigrew, 1992; Stangor & McMillan, 1992) was expected to occur, that is, old objects should be remembered better after the presentation of a young prime, while young objects should be remembered better after the presentation of an old prime. Under conditions of cognitive load, the incongruency effect should disappear due to the lack of cognitive resources to form inter-item associations during the encoding of incongruent information.
2.5.2Method Participants
Eighty-three students (42 female, 41 male) of the Universität Konstanz either participated for course credit (psychology students) or were paid 3.50 Euros in exchange for their participation (students of other subjects). The average age of participants was 23 years (SD
= 2.54).
Design
The study followed a 2 (Cognitive Load: no cognitive load vs. visual load) ° 2 (Prime:
old men vs. young men) ° 2 (Target: old objects vs. young objects) mixed model design with repeated-measures on the last two factors. The dependent variables were free recall and recognition tasks testing long-term memory of stereotype-inconsistent and stereotype-consistent information.
Procedure
The experiment was conducted on personal computers using presentation software10 and participants were run individually. Participants were informed that this study investigated the perception of faces and memory of objects (see Appendix G, p. 184-185).
On each trial, participants were first presented with a matrix consisting of 5 × 5 cells in the center of the screen and shown against a medium gray background. This background was presented throughout the experiment. In the no load condition, five black dots formed a cross in the center of the matrix: participants were asked to fixate on it until the next slide appeared, thus concentrating on the task. In the visual load condition, the five points were randomly distributed among the 25 cells. Participants were to memorize the pattern of dots for later verification. Right after the presentation of the matrix, the face of an old man or of a young man was primed for 150 ms. Participants were instructed to form an impression of the presented face
10 Dell DIMENSION XPS-Z, 261.424 KB RAM, operation system: Microsoft Windows 2000
to ensure that the faces were not ignored. The prime was immediately replaced by six photos of objects serving as targets. On each trial two old objects, two young objects, and two neutral objects were presented in randomized positions for 800 ms. Participants were to memorize these objects without knowledge of their stereotypicality. Subsequently, the grid with the five dots was presented again. Participants in the no load condition were again to fixate on the cross of dots and press the space key when they were ready to continue.
In the visual load condition, in half of the trials one point of the grid was moved one space. In the other half of the trials, the distribution of the dots was the same as previously seen.
Participants were to decide if the test configuration of dots, arrayed within the grid, matched the configuration presented earlier by pressing the respective key (J for ‘yes’ and N for ‘no’). The presentation of either a different (no) or the same (yes) matrix was randomized for the 36 critical trials. After participants had made a decision and pressed one of the keys, a free recall test followed. Responses were entered by typing the words. Participants were to type as many of the previously presented (six) objects as possible. Once they had finished, they could press the F12 key to go on, even if they had not rememberd all six of the objects. The free recall test was replaced by a recognition test. Twelve photos of objects were presented and participants had to decide which objects they had previously seen by clicking on them with the mouse. The recognition task continued until the participant had marked six objects.
Each participant completed four practice trials after which he or she could ask questions if anything remained unclear. Thirty-six critical trials followed, which were then included in the analysis. At the end of the experiment, participants filled out a paper and pencil questionnaire with demographic information and questions about the manipulation, were thanked, paid, and fully debriefed (examples of a trial in the no load and the visual load condition, respectively, see Figure 7 and 8).
Figure 7. Example of a trial in the no load condition.
Figure 8. Example of a trial in the visual load condition.
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Pretests and material
In order to select objects used in everyday life that were either classified as being strongly associated with old people, young people, or neither of these two social groups, several pretests were run. Participants who took part in these pretests were German students, who did not participate in the main experiment.
First, ten students were asked to write down objects typically associated with old people and whether these objects were more typical of men or of women. An additional ten students were asked to write down objects typically associated with young people and also whether these objects are more typical of men or of women. The ten objects, most frequently identified with a
“young male” (i.e., objects that were identified as typical of young men) and ten objects identified as an “older male” (i.e., objects that were identified as typical of older men) were chosen and pictures of these objects were retrieved from the internet.
Additionally, a search for photos of neutral objects was run on the internet. Finally, pictures of 109 old, young, and neutral objects were selected, and included one to four different photos per object. These 109 pictures were shown to 30 participants who were asked to name each object, rate what kind of person might be the owner of this object, and afterwards whether it better fits an old man, a young man, or neither of them. Of these 109 objects, the twelve objects that were correctly named and allocated to an old and young man respectively were selected. Twelve neutral pictures that were neither allocated to a young nor to an old man were also chosen.
Furthermore, black and white photos of young and old faces (private or from the internet) were searched for. Six pictures of old men and six pictures of young men were presented to 20 participants who were to decide which of the pictures were the most typical of young and the most typical of old men. The two photos that were most characteristic of old men and the two photos that were most characteristic of young men were selected. These four faces served as primes in the main experiment.
At last, the 36 selected objects were presented together with the four selected faces. A new sample of 28 students were asked how likely it is that these men would own these objects.
The six old and the six young objects that were the most highly rated, in addition to the six neutral objects that were the least highly rated, served as targets in the main experiment (see Appendix G, p. 183).
Load manipulation. Participants in the no goal condition were presented a 5 ¯ 5 grid in which five dots formed a cross in the middle of the matrix. In the visual load condition, the five dots were randomly distributed with several limitations (e.g., no more than two dots could fall in a straight line), ensuring that the memorization of the distribution was not too easy and
that the distribution was similar to that of the other trials. In the second presentation, the distribution of the dots was different from the first presentation in half of the trials. In each case, only one dot was displaced one space.
Primes. Primes were digitalized black and white photographs that included two typical faces of old men and two typical faces of young men. Pictures were presented in randomized order at a resolution of 227 ¯ 283 pixels. Thus, each photo was presented nine times (see Appendix G, p. 183).
Targets. Target stimuli consisted of digitalized black and white photographs of 18 objects used in everyday life. The following six objects were assessed as very typical for old men in several pretests (see above): pipe, dentures, hat, cane, hearing device, and walker (“old targets”). The following six targets were assessed as very typical for young men in the pretests:
mobile phone, condom, laptop, mp3 player, backpack, and memory stick (i.e., “young targets”).
Finally, the following six objects were rated as neither associated with old men nor young men in the pretests: fork, money, pen, spoon, knife, and table (i.e., “neutral targets”). Theses pictures were presented in randomized order at a resolution of 91 ¯ 91 pixels. In each trial six objects were presented including two old, two young, and two neutral objects. Thus, each object was presented 12 times and each object’s category (old, young, neutral) was presented 72 times, 36 times after the presentation of an old prime and 36 times after the presentation of a young prime (see Appendix G, p. 183).
2.5.3Results
Error rates and excluded data
Participants in the visual load condition were asked to classify the matrix as old or new, as amanipulation check. Gilbert and Hixon (1991) reported that it is difficult to interpret the performance of the secondary task. If participants classified only a small number of matrices as correct it either shows that they were strongly engaged in the memory task and neglected the secondary task or that the dual-task manipulation was highly effective and capacity was thus strained. Further, if participants classified most matrices correctly, it implies that they neglected the memory task. However to reduce the likelihood of such an effect, Gilbert and Hixon (1991) suggested establishing an a priori cutoff (see also Sherman & Frost, 2000).
Thus, participants that made more than 18 errors (out of 36 possible answers) were excluded from the analyses. Of the 43 load participants, three were excluded from analyses due to error rates of 19 and one due to an error rate of 21. Forty participants remained in the no load condition and 39 in the visual load condition.
Manipulation checks
In order to check the successful manipulation of cognitive load of the visuospatial sketchpad (see Appendix G, p. 186-189, participants were asked “How much effort did you have to put forth to perform the pattern task (matrix)?” (Wie schwer fiel es Ihnen, jeweils die Mustererkennungsaufgabe (Gitternetz) durchzuführen?). Participants marked their answers on a 70 millimeter (2.76 inch) analogue scale labeled not much at all on the left-hand side and a lot on the right-hand side. An ANOVA using Cognitive Load (no load vs. visual load) as the independent variable was computed. Results indicated that load participants (M = 36.56, SD = 17.80) reported expending more effort than participants in the no load condition (M = 21.48, SD = 20.15), F(1, 77) = 12.41, p = .001, η² = .14.
Participants were asked how difficult it was for them to recall (“How difficult was it for you to recall the six objects each time?” – Wie schwer fiel es Ihnen, jeweils die sechs Gegenstände zu benennen?) and to recognize (“How difficult was it for you to recognize the six out of twelve objects each time?” – Wie schwer fiel es Ihnen, jeweils die sechs Gegenstände aus den zwölf auszuwählen?) the six objects. A 2 between (Cognitive Load: no load vs. visual load) × 2 within (Memory Test:
no load vs. visual load) ANOVA revealed a significant main effect of memory tests, F(1, 77) = 23.18, p < .001, η² = .23. A t-test for paired samples showed that participants reported more difficulty recalling (M = 46. 91, SD = 15.23) versus recognizing (M = 39.51, SD = 16.83) the objects, t(78) = 4.85, p < .001. No further effects of the ANOVA reached significance, F’s < 1.
Free Recall
For the analyses of the dependent variables, the proportion of responses was calculated (in percent) for the various variables. A 2 between (Cognitive Load: no load vs. visual load) × 2 within (Prime: old vs. young) × 2 within (Target: old vs. young) repeated-measures analysis of variance was performed. There was a significant main effect of Cognitive Load, F(1, 77) = 10.28, p < .01, η²=.12: participants in the visual load condition (M = 52.94, SD = 9.77) remembered less objects than the no load participants (M = 60.38, SD = 10.83). There was also a significant main effect of Target, F(1, 77) = 4.87, p < .05, η²=.06, indicating that old objects (M = 57.86, SD = 12.22) were remembered better than young objects (M = 55.56, SD = 11.46), as well as a significant effect of Prime, F(1, 77) = 4.77, p < .05, η²=.06, indicating that more objects were remembered after the presentation of an old prime (M = 57.74, SD = 11.49) than after the presentation of a young prime (M = 55.68, SD = 11.88). No further effects reached significance, F`s < 1 (see Figure 9).
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Figure 9. Probability of recalling old targets and young targets as a function of the presentation of an old or a young prime and cognitive load.
Recognition
For the analysis of the recognition performance, a 2 between (Cognitive Load: no load vs. visual load) × 2 within (Prime: old vs. young) × 2 within (Target: old vs. Young) ANOVA was conducted. Results yielded a marginally significant Cognitive Load × Prime × Target interaction, F(1, 77) = 3.33, p = .07, η² = .04, a marginally significant Prime × Target interaction, F(1, 77) = 3.18, p = .08, η² = .04, a marginally significant main effect of Target, F(1, 77) = 2.70, p = .11, η² = .03, and a significant main effect of Cognitive Load, F(1, 77) = 5.74, p < .05, η² = .07, indicating that participants not under cognitive load identified more objects correctly (M = 74.83, SD = 7.15) than participants under cognitive load (M = 70.92, SD =74.83). No further effects of this overall ANOVA were significant, F’s < 1.
For a further analysis of the 3-way interaction, a repeated-measures ANOVA with participants in the no load condition only revealed a significant Prime × Target interaction, F(1, 39)
= 6.16, p < .05, η² = .14, indicating that recognition performance of the no load participants was higher for old objects (M = 77.15, SD = 9.02) than for young objects (M = 72.36, SD = 11.16) if they had previously seen an old face, t(39) = 2.66, p < .05. Additionally, old objects were correctly identified more often if an old face was presented as the prime (M = 77.15, SD = 9.02) than if a young face was presented as the prime (M = 74.38, SD = 9.61), t(39) = 1.76, p < .05 (one-sided). Further, recognition performance for young objects was higher if a young face (M =
75.42, SD = 10.13) was presented than if an old face (M = 72.36, SD = 11.16) was presented as prime beforehand, t(39) = 1.81, p < .05 (one-sided). No other effects were significant (t < 1).
Repeated measures with participants in the cognitive load condition did not reveal any significant effects (main effect Target: F(1, 38) = 1.14, p = .29, η² = .03, further effects: F’s < 1).
Furthermore, planned comparisons were conducted for the four dependent variables by load conditions. These analyses revealed that consistent information (young prime followed by a young target, old prime followed by an old target) was influenced by visual load, while inconsistent information (young prime followed by an old target, old prime followed by a young target) was not impaired: Old targets were remembered worse by cognitive load participants (M
= 72.01, SD = 9.13) than by no load participants (M = 77.15, SD = 9.02) after the presentation of an old prime, t(77) = 2.52, p < .05. Similarly, young targets were remembered worse after the presentation of a young prime in the cognitive load condition (M = 69.80, SD = 9.58) compared to the no load condition (M = 75.42, SD = 10.13), t(77) = 2.53, p < .05. However, there were no differences found for old targets after the presentation of a young prime (no load: M = 74.38, SD = 9.61; visual load: M = 71.44, SD = 10.72; t(77) = 1.28, p = .20) or for young targets after the presentation of an old prime, independent of load (no load: M = 72.36, SD = 11.16; visual load: M = 70.44, SD = 10.48; t < 1; see Figure 10).
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Figure 10. Probability of recognizing old targets and young targets as a function of prime and cognitive load (* p < .05).
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2.5.4Discussion
This study was conducted as a first attempt to investigate load effects on visual memory of stereotype-relevant information. It was foremost observed that blocking the visuospatial sketchpad led to a clear impairment in the recall and recognition of all kinds of visually presented objects, in comparison to a condition that did not block cognitive resources. Thus, retaining a dot configuration in working memory consumes resources that are not available for the encoding and storing of visual material. This effect appeared independent of both kinds of primes, that is, faces of old and young men. The results indicate that the paradigm developed to block visuospatial resources was successful and additionally replicated former studies that used similar methods to investigate load effects on visual tasks (e.g., Kruley et al., 1994; Sims &
Hegarty, 1997). Nevertheless, not only should overall memory performance be decreased, but load should also have influenced the processing of social information.
In the free recall task, only main effects were observed. Although an interaction was expected, main effects indicate that the pretested material discriminated between objects (old vs.
young), primes (old vs. young), and manipulation (no load vs. visual load). Old objects were generally remembered better than young objects; objects were generally remembered better after the presentation of an old face than after the presentation of a young face. Yet, participants in this study were exclusively young people. Old objects may essentially represent new and unfamiliar information to the participants. A phenomenon known as novel popout postulates that novel stimuli embedded in a set of familiar stimuli attract more attention (Lubow & Kaplan, 1997; Strayer & Johnston, 2000). Maybe old objects and old primes were more extensively encoded and remembered because this material was novel to the perceiver and thus attracted more attention (see also Friedman, 1979).
Another reason is perhaps that stereotypic beliefs about the elderly are mainly negative (see Montepare & Zebrowitz, 2002; Pasupathi, Carstensen, & Tsai, 1995; Zebrowitz &
Montepare, 2000). Perdue and Gurtman (1990), for example, observed in an affective priming paradigm that the concept “old” holds a negative connotation contradictory to the concept
“young”. Moreover, Castelli and colleagues (2005) reported a study in which evidence was found that “pictures portraying young people automatically activated approach motor responses whereas pictures of old people automatically activated avoidance motor responses” (p. 136).
Furthermore, research using the Implicit Association Test (IAT) repeatedly reveals negative attitudes towards elderly persons (e.g., Kite & Johnson, 1988; Nosek, Banaji, &
Furthermore, research using the Implicit Association Test (IAT) repeatedly reveals negative attitudes towards elderly persons (e.g., Kite & Johnson, 1988; Nosek, Banaji, &