Irene Reppa

Inhibition of return for objects and locations in static displays

When orienting attention, inhibition mechanisms prevent the return of attention to previously examined stimuli. This inhibition of the return of attention (IOR) has been shown to be associated additively with location- and object-based representations. That is, when static objects are attended, IOR is associated with both the object and the location cued, and hence IOR is larger than when only spatial location is attended. Recently McAuliffe, Pratt, and O’Donnell (2001) failed to observe such additive effects except under a narrow set of conditions (at short cue-target intervals and using mixed blocks in which object- and pure location-based effects were probed in the same display). The present study shows that additive IOR effects are observed under conditions that violate all of these boundary conditions. The results also show that IOR is modulated by internal structural properties of objects. These findings are consistent with the hypothesis that IOR operates over functionally independent objectand location-based frames of reference.

An Empirical Study on Using Visual Embellishments in Visualization

In written and spoken communications, figures of speech (e.g., metaphors and synecdoche) are often used as an aid to help convey abstract or less tangible concepts. However, the benefits of using rhetorical illustrations or embellishments in visualization have so far been inconclusive. In this work, we report an empirical study to evaluate hypotheses that visual embellishments may aid memorization, visual search and concept comprehension. One major departure from related experiments in the literature is that we make use of a dual-task methodology in our experiment. This design offers an abstraction of typical situations where viewers do not have their full attention focused on visualization (e.g., in meetings and lectures). The secondary task introduces “divided attention”, and makes the effects of visual embellishments more observable. In addition, it also serves as additional masking in memory-based trials. The results of this study show that visual embellishments can help participants better remember the information depicted in visualization. On the other hand, visual embellishments can have a negative impact on the speed of visual search. The results show a complex pattern as to the benefits of visual embellishments in helping participants grasp key concepts from visualization.

The modulation of inhibition of return by objectinternal structure: Implications for theories of object-based attentional selection

Recently, Vecera, Behrmann, and McGoldrick (2000), using a divided-attention task, reported that targets are detected more accurately when they occur on the same structural part of an object, suggesting that attention can be directed toward object-internal features. We present converging evidence using the object-based inhibition of return (IOR) paradigm as an implicit measure of selection. The results show that IOR is attenuated when cues and targets appear on the same part of an object relative to when they are separated by a part boundary. These findings suggest that object-based mechanisms of selection can operate over shape representations that make explicit information about objectinternal structure.

Why do I like It? the Relationships between Icon Characteristics, user Performance and Aesthetic Appeal

Until recently the guiding tenet in human-computer interaction was that any interface must be easy to learn and use. However, it has been increasingly recognized that the appeal of the interface to the user and their enjoyment of it is also important. The aim of the current study was to examine the nature of the relationships between icon characteristics, user performance, and aesthetic appeal. When participants were asked to rate the appeal of a corpus of icons, it was found that the same icon characteristics predicted appeal as those predicting user performance. The theoretical and practical implications of the remarkable similarity in the factors determining appeal and usability are discussed.

The Structure of Three-Dimensional Object Representations in Human Vision: Evidence from Whole-Part Matching.

This article examines how the human visual system represents the shapes of 3-dimensional (3D) objects. One long-standing hypothesis is that object shapes are represented in terms of volumetric component parts and their spatial configuration. This hypothesis is examined in 3 experiments using a whole-part matching paradigm in which participants match object parts to whole novel 3D object shapes. Experiments 1 and 2, consistent with volumetric image segmentation, show that whole-part matching is faster for volumetric component parts than for either open or closed nonvolumetric regions of edge contour. However, the results of Experiment 3 show that an equivalent advantage is found for bounded regions of edge contour that correspond to object surfaces. The results are interpreted in terms of a surface-based model of 3D shape representation, which proposes edge-bounded 2-dimensional polygons as basic primitives of surface shape.

Surface but not volumetric part structure mediates three-dimensional shape representation: Evidence from part–whole priming

The decomposition of three-dimensional (3-D) objects into shape primitives consisting of geometric volumes is a key proposal of some theories of object recognition. It implicitly assumes that recognition involves volumetric completion—the derivation of a three-dimensional structure that comprises inferred shape properties, such as surfaces, that are not directly visible due to self-occlusion. The goal of this study was to test this claim. In Experiment 1 participants memorized novel objects and then discriminated these from previously unseen objects. Targets were preceded by primes containing a subset of object surfaces that either matched those visible in the whole objects or that could only be inferred through volumetric completion. The results showed performance benefits through priming from visible surfaces but not from inferred surfaces. In Experiment 2, we found equivalent priming for part-primes containing two visible surfaces from the same volumetric part and for primes containing one surface from each of two volumes. These results challenge the view that 3-D object recognition is mediated by shape primitives comprising geometric volumes. Instead, the results support an alternative model that proposes that 3-D shapes are represented as a non-volumetric surface-based structural description.

The representation of response effector and response location in episodic memory for newly acquired actions: evidence from retrieval-induced forgetting

Information retrieval can cause forgetting for related but non-retrieved information. Such retrieval-induced forgetting (RIF) has been previously found for semantically and episodically related information. The current study used RIF to examine whether response effector and location are encoded explicitly in action memory. Participants learned unique touchscreen responses to ten novel objects. Correct actions to each object involved left-hand or right-hand pushing of one of four possible object buttons. After learning, participants practiced two of the ten object-specific sequences. Unpracticed actions could share hand only, button only, both hand and button, or neither hand nor button, with the practiced actions. Subsequent testing showed significant RIF (in retrieval accuracy and speed measures) for actions that shared hand only, button only, or both hand and button with the practiced action. The results have implications for understanding the representations mediating episodic action memory, and for the potential of RIF as a tool for elucidating feature-based representations in this and other domains.

Visual Aesthetic Appeal Speeds Processing of Complex but not Simple Icons

Over the last decade there has been a shift in emphasis from interface usability to interface appeal. Very few studies, however, have examined the link between the two. The current study examined the possibility that aesthetic appeal may affect user performance. In a visual search task designed to mimic user searches of interface displays, participants were asked to search for a target icon in an array of distractors. Target icons were varied orthogonally along two dimensions, complexity (which is known to affect visual search for icons in displays) and aesthetic appeal. The results showed that visually simple icons were found faster than visually complex icons, replicating previous findings. More importantly, aesthetic appeal interacted with icon complexity, significantly reducing search times for complex but not simple icons. These findings provide empirical evidence to support the idea that aesthetic appeal can influence performance.

Structure-based modulation of inhibition of return is triggered by object-internal but not occluding shape features

When attention is oriented to an object it is inhibited from returning to the same object following a short delay. This inhibition-of-return (IOR) effect is modulated by an edge discontinuity presented between cue and target—an effect referred to as structure-based modulation of IOR. Here we examined two alternative accounts for the structure-based modulation effect. On one account the modulation is caused by the presence of any intervening feature between cue and target. On another account the modulation is caused by edge-bounded (i.e., closed) regions of space, on which space-based selection mechanisms operate. We presented cues and targets on unsegmented and internally or externally segmented rectangles to examine the two alternative accounts for the effect. Contrary to the predictions of the two alternative accounts, structure-based modulation of IOR was found with the internally but not with the externally segmented displays. This supports our hypothesis that object-based IOR arises from perceptually complete and internally structured object representations.

Ease of icon processing can predict icon appeal

Correlations between subjective ratings of interface usability and appeal have been frequently reported. This study examined the possibility that the relationship between usability and appeal are underpinned by implicit perceptions of ease of processing which act as a heuristic in making judgments of appeal. Ease of processing was manipulated by varying the amount of experience participants gained with icons in a search task prior to judging appeal, as well as varying the familiarity and visual complexity of the icons presented. These manipulations systematically affected response times in the search task (an objective measure of usability). The effects observed in appeal judgments followed thesame pattern as for search times, demonstrating that ease of processing predicts judgments of appeal. This suggests that our understanding of interface appeal needs to be predicated on an appreciation of the factors affecting the ease with which information on an interface is processed.