Kim-Phuong L. Vu

Stimulus-Response Compatibility Principles : Data, Theory, and Application

STIMULUS-RESPONSE COMPATIBILITY AND SELECTION OF ACTION: BASIC CONCEPTSIntroductionClassic StudiesTerminology and DistinctionsTechniques for Studying S-R CompatibilityModels for S-R Compatibility EffectsChapter SummaryFACTORS IN ADDITION TO S-R COMPATIBILITY THAT AFFECT RESPONSE-SELECTION EFFICIENCYIntroductionThe Speed-Accuracy TradeoffUncertainty and Number of AlternativesResponse-Precuing EffectsSequential EffectsInfluence of Practice on Set-Size Effects and Sequence LearningChapter SummaryBASIC STIMULUS-RESPONSE COMPATIBILITY EFFECTSIntroductionSpatial Stimuli and ResponsesVerbal and Nonverbal S-R ModesOther Element-Level S-R Compatibility EffectsChapter SummaryCORRESPONDENCE OF IRRELEVANT STIMULUS INFORMATION AND RESPONSES: THE SIMON EFFECTIntroductionSpatial Stimuli and ResponsesSimon-Type Effects for Other Stimulus and Response DimensionsChapter SummaryS-R COMPATIBILITY EFFECTS FOR MULTIDIMENSIONAL STIMULUS AND RESPONSE SETSIntroductionTwo-Dimensional Nonspatial Stimuli Mapped to Keypress ResponsesThe Right-Left Prevalence Effect for Two-Dimensional Spatial Stimuli and ResponsesSimon Effects for Two-Dimensional Spatial Stimuli and ResponsesStatic and Dynamic DimensionsJudgment and Decision-MakingChapter SummaryREVERSING THE SIMON EFFECT FOR IRRELEVANT LOCATIONIntroductionThe Hedge and Marsh ReversalManipulating Percentages of Corresponding and Noncorresponding TrialsEffects of Intermixed Location-Relevant MappingsTransfer from a Prior Spatial Mapping to the Simon TaskChapter SummaryCONSEQUENCES OF MIXED MAPPINGS AND TASKSIntroductionMixing Compatible and Incompatible Mappings in Spatial Choice TasksMixing Nonspatial S-R MappingsAccounts for Elimination of the S-R Compatibility Effect with Mixed MappingsMixing Location-Relevant and -Irrelevant Trials: The S-R Compatibility EffectAccounts for the Elimination of SRC Effects with Mixed Location-Relevant and -Irrelevant TrialsComparison of Mixed Mappings and Trial TypesA Negative Correspondence Effect for Masked StimuliChapter SummaryCOMPATIBILITY EFFECTS FOR ORTHOGONAL DIMENSIONSIntroductionUp-Right/Down-Left Mapping AdvantageInfluences of Hand, Hand Posture, and Response Eccentricity on Orthogonal S-R CompatibilityCorrespondence of Asymmetric Codes as a General Principle of Binary-Choice ReactionsTasks with More than Two AlternativesChapter SummaryPOPULATION STEREOTYPES FOR DIRECTION OF MOTION AND COLOR, WORD, AND PICTURE ASSOCIATIONSIntroductionLinear Display Indicators and their Relations to ControlsRotary Displays and their ControlsOther Population StereotypesChapter SummarySTIMULUS-RESPONSE COMPATIBILITY EFFECTS IN DUAL-TASK PERFORMANCEIntroductionThe PRP Effect and the Central Bottleneck ModelSimon Effects for Irrelevant Stimulus LocationConsistency of MappingsCrosstalk between TasksC

Improving password security and memorability to protect personal and organizational information

Personal information and organizational information need to be protected, which requires that only authorized users gain access to the information. The most commonly used method for authenticating users who attempt to access such information is through the use of username-password combinations. However, this is a weak method of authentication because users tend to generate passwords that are easy to remember but also easy to crack. Proactive password checking, for which passwords must satisfy certain criteria, is one method for improving the security of user-generated passwords. The present study evaluated the time and number of attempts needed to generate unique passwords satisfying different restrictions for multiple accounts, as well as the login time and accuracy for recalling those passwords. Imposing password restrictions alone did not necessarily lead to more secure passwords. However, the use of a technique for which the first letter of each word of a sentence was used coupled with a requirement to insert a special character and digit yielded more secure passwords that were more memorable.

Improving computer security for authentication of users: influence of proactive password restrictions.

Entering a username—password combination is a widely used procedure for identification and authentication in computer systems. However, it is a notoriously weak method, in that the passwords adopted by many users are easy to crack. In an attempt to improve security, proactive password checking may be used, in which passwords must meet several criteria to be more resistant to cracking. In two experiments, we examined the influence of proactive password restrictions on the time that it took to generate an acceptable password and to use it subsequently to log in. The required length was a minimum of five characters in Experiment 1 and eight characters in Experiment 2. In both experiments, one condition had only the length restriction, and the other had additional restrictions. The additional restrictions greatly increased the time it took to generate the password but had only a small effect on the time it took to use it subsequently to log in. For the five-character passwords, 75% were cracked when no other restrictions were imposed, and this was reduced to 33% with the additional restrictions. For the eight-character passwords, 17% were cracked with no other restrictions, and 12.5% with restrictions. The results indicate that increasing the minimum character length reduces crackability and increases security, regardless of whether additional restrictions are imposed.

Mixing compatible and incompatible mappings: Elimination, reduction, and enhancement of spatial compatibility effects

In two-choice tasks, the compatible mapping of left stimulus to left response and right stimulus to right response typically yields better performance than does the incompatible mapping. Nonetheless, when compatible and incompatible mappings are mixed within a block of trials, the spatial compatibility effect is eliminated. Two experiments evaluated whether the elimination of compatibility effects by mixing compatible and incompatible mappings is a general or specific phenomenon. Left–right physical locations, arrow directions, and location words were mapped to keypress responses in Experiment 1 and vocal responses in Experiment 2. With keypresses, mixing compatible and incompatible mappings eliminated the compatibility effect for physical locations and arrow directions, but enhanced it for words. With vocal responses, mixing significantly reduced the compatibility effect only for words. Overall, the mixing effects suggest that elimination or reduction of compatibility effects occurs primarily when the stimulus-response sets have both conceptual and perceptual similarity. This elimination may be due to suppression of a direct response-selection route, but to account for the full pattern of mixing effects it is also necessary to consider changes in an indirect response-selection route and the temporal activation properties of different stimulus-response sets.

Spatial coding in two dimensions

There has been growing interest in exploring human performance for situations in which stimuli and/or responses vary along both horizontal and vertical dimensions. Earlier studies indicated that there is a prevalence of the horizontal dimension over the vertical dimension in the spatial codes that are used for response selection. We review evidence about spatial coding for 2-D stimulus—response sets and accounts that have been proposed for explaining how it takes place. Particular attention is devoted to the relative salience account, which provides the most comprehensive explanation of 2-D spatial coding. We also evaluate the influence of speed of spatial code formation, number of reference frames, and learning on subjects’ performance in 2-D tasks.

Mixing location-irrelevant and location-relevant trials: Influence of stimulus mode on spatial compatibility effects

The performance advantage for spatially compatible mappings of physical locations to keypress responses, relative to incompatible mappings, is eliminated when stimulus color, rather than location, is relevant on half of the trials. In Experiment 1, we compared the effects of mixing for different stimulus modes (physical locations, arrow directions, and location words) to determine whether this elimination of the stimulus—response compatibility (SRC) effect would generalize to other stimulus modes. The SRC effect was unaffected when the location information was conveyed by arrows and was amplified when the location information was conveyed by words. In Experiment 2, we used vocalleft—right responses instead of keypresses, and the SRC effects for all three stimulus modes were enhanced by mixing. In both experiments, for all stimulus modes, mixing reduced or reversed correspondence effects for trials on which the location information was irrelevant when the mapping for those trials on which it was relevant was incompatible. These findings suggest that when trial types are mixed, direct activation of the corresponding response, regardless of mapping, does not occur for physical locations mapped to keypresses. However, such activation does occur when stimuli or responses are verbal, apparently because performance is mediated in part by activation of a verbal name code for the stimulus.

Determinants of right-left and top-bottom prevalence for two-dimensional spatial compatibility.

When stimulus and response sets vary along horizontal and vertical dimensions, the horizontal dimension is more dominant than the vertical one, an effect called right-left prevalence. Three accounts have been proposed that attribute the effect to a reduced ability to code vertical locations when horizontal codes are also present, the use of right-left effectors, or a difference in salience of the 2 dimensions. The accounts differ in terms of whether the ability to code and process the 2 dimensions is of limited capacity and whether the prevalence effect is a consequence of the effectors used for responding. The authors report 4 experiments that evaluated these issues. Results indicate that use of right-left effectors is important to the right-left prevalence effect because it increases the salience of the horizontal dimension. However, a top-bottom prevalence effect can be obtained if the vertical dimension is made more salient.

Influences on the Simon Effect of Prior Practice with Spatially Incompatible Mappings: Transfer within and between Horizontal and Vertical Dimensions

The Simon effect refers to the fact that for tasks in which stimulus location is irrelevant and a nonspatial attribute is relevant, responses are typically faster when stimulus and response locations correspond than when they do not. Two experiments examined the influence of prior practice with an incompatible relevant spatial mapping on the Simon effect as a function of the dimension (vertical or horizontal) along which the stimuli and responses varied in practice and transfer sessions. With 72 practice trials, the Simon effect in the transfer session was eliminated only when the spatial dimension was horizontal for both practice and transfer. With 600 practice trials, the Simon effect was eliminated for all combinations of practice and transfer dimensions, with noncorresponding responses showing an advantage when the dimension was horizontal for both practice and transfer. Within-dimension transfer effects for the horizontal dimension after a small amount of practice can be attributed to reactivation of specific stimulus—response associations defined for the practice task. However, the between-dimension transfer effects evident after a larger amount of practice cannot be explained in this manner and suggest that the subjects acquired a general procedure of responding opposite to the stimulus location.

The prevalence effect in two-dimensional stimulus-response compatibility is a function of the relative salience of the dimensions

When stimulus-response (S-R) sets vary along horizontal and vertical dimensions, a right-left prevalence effect is often obtained in which the horizontal compatibility effect is larger than the vertical compatibility effect. Vu and Proctor (2001) showed that the prevalence effect varies as a function of the dimension made salient by the response configuration. A salient features coding interpretation of this result implies that manipulating the salience of the stimulus display should produce similar results and that S-R translation should be fastest when salient features of the stimulus and the response sets correspond. Experiment 1 manipulated spatial proximity to make the vertical or the horizontal stimulus dimension salient. Neutral displays yielded a typical right-left prevalence effect, and this effect was enhanced by horizontal-salient displays and eliminated by vertical-salient displays. Experiments 2 and 3 showed that the benefit for horizontal (or vertical) compatibility was larger when the salient features of both the stimulus and the response sets emphasized the horizontal (or the vertical) dimension than when only one did. The results support salient features coding as an explanation for the prevalence effect obtained with two-dimensional S-R arrangements.

Transfer effects of incompatible location-relevant mappings on a subsequent visual or auditory simon task.

Two experiments investigated the influence of practice with an incompatible mapping of left and right stimuli to keypress responses on performance of a subsequent Simon task, for which stimulus location was irrelevant, after a delay of 5 min or 1 week. In Experiment 1, the visual Simon effect was eliminated when the practice modality was auditory and reversed to favor noncorresponding responses when it was visual, and there was no significant effect of delay interval. In Experiment 2, significant auditory Simon effects were obtained that did not vary as a function of practice modality, with delay having only a marginal effect on the magnitude of the Simon effect. The elimination of the visual Simon effect in the transfer session is most likely due to the short-term stimulus-response associations defined for the incompatible spatial mapping remaining active during the transfer session. Because the auditory Simon effect is stronger than the visual one, more practice with the incompatible mapping may be necessary to produce reliable transfer effects for it.