Stimulus type, level of categorization, and spatial-frequencies utilization: Implications for perceptual categorization hierarchies (original) (raw)
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Multiple object categorization and effect of spatial frequencies
A process of interaction between objects and scene is widely investigated but much less attention is paid to the interaction between objects in multiple objects stimuli. In psychophysical experiment, we presented one, two, or three visual objects simultaneously for 100 ms and then asked subjects to answer whether objects belong to the same category (Experiments 1 and 2), or whether afterwards presented probe-word signify an object that was presented (Experiments 3 and 4). Interestingly, performance accuracy and reaction time did not depend on the number of objects if they belonged to the same category, but performance deteriorated when more categories were presented. Filtering out high or low spatial frequencies did not affect performance peculiarities of the objects of the same or different categories. The findings support assumption that visual objects of the same category could be identified simultaneously but the different categories are identified successively.
The preferred level of face categorization depends on discriminability
Psychonomic Bulletin & Review, 2008
People usually categorize objects more quickly at the basic level (e.g., "dog") than at the subordinate (e.g., "collie") or superordinate (e.g., "animal") levels. Notable exceptions to this rule include objects of expertise, faces, or atypical objects (e.g., "penguin," "poodle"), all of which show faster than normal subordinate-level categorization. We hypothesize that the subordinate-level reaction time advantage for faces is influenced by their discriminability relative to other faces in the stimulus set. First, we replicated the subordinate-level advantage for faces (Experiment 1) and then showed that a basic-level advantage for faces can be elicited by increasing the perceptual similarity of the face stimuli, making discrimination more difficult (Experiment 2). Finally, we repeated both effects within subjects, showing that individual faces were slower to be categorized in the context of similar faces and more quickly categorized among diverse faces (Experiment 3).
The prioritization of perceptual processing in categorization
Attention, Perception, & Psychophysics, 2010
In three experiments, the effects of selective attention on perceptual processes in a complex multidimensional object categorization task were investigated. In each experiment, participants completed a perceptual-matching task to gain estimates of the perceptual salience of each stimulus dimension, then a categorization task using the same stimuli. In Experiments 1 and 2, the perceptual processing of stimulus dimensions was faster when dimensions were more diagnostic of category membership, regardless of their perceptual salience. Experiment 3 demonstrated that this prioritization of perceptual processing was evident even when stimuli were presented in unpredictable locations during categorization, indicating that the physical characteristics of the stimulus guide selective attention to diagnostic stimulus dimensions.
PLoS ONE, 2013
A much-debated question in object recognition is whether expertise for faces and expertise for non-face objects utilize common perceptual information. We investigated this issue by assessing the diagnostic information required for different types of expertise. Specifically, we asked whether face categorization and expert car categorization at the subordinate level relies on the same spatial frequency (SF) scales. Fifteen car experts and fifteen novices performed a category verification task with spatially filtered images of faces, cars, and airplanes. Images were categorized based on their basic (e.g. ''car'') and subordinate level (e.g. ''Japanese car'') identity. The effect of expertise was not evident when objects were categorized at the basic level. However, when the car experts categorized faces and cars at the subordinate level, the two types of expertise required different kinds of SF information. Subordinate categorization of faces relied on low SFs more than on high SFs, whereas subordinate expert car categorization relied on high SFs more than on low SFs. These findings suggest that expertise in the recognition of objects and faces do not utilize the same type of information. Rather, different types of expertise require different types of diagnostic visual information.
Traditional models of recognition and categorization proceed from registering low-level features, perceptually organizing that input, and linking it with stored representations. Recent evidence, however, suggests that this serial model may not be accurate, with object and category knowledge affecting rather than following early visual processing. Here, we show that the degree to which an image exemplifies its category influences how easily it is detected. Participants performed a two-alternative forced-choice task in which they indicated whether a briefly presented image was an intact or phase-scrambled scene photograph. Critically, the category of the scene is irrelevant to the detection task. We nonetheless found that participants “see” good images better, more accurately discriminating them from phase-scrambled images than bad scenes, and this advantage is apparent regardless of whether participants are asked to consider category during the experiment or not. We then demonstrate that good exemplars are more similar to same-category images than bad exemplars, influencing behavior in two ways: First, prototypical images are easier to detect, and second, intact good scenes are more likely than bad to have been primed by a previous trial.
Visual Cognition, 2011
In two experiments, we test predictions regarding processing advantages/disadvantages for natural objects and artefacts in visual object recognition. Varying three important parameters—degree of perceptual differentiation, stimulus format, and stimulus exposure duration—we show how different category-effects can be provoked in normal subjects on the same task. We interpret the results in light of the Pre-semantic Account of Category Effects (PACE; Gerlach, 2009), and conclude that category-effects do not reflect absolute processing differences between categories. Rather, category-effects are products of common operations which are differentially affected by the structural similarity among objects (with natural objects being more structurally similar than artefacts). The potentially most important aspect of the present study is the demonstration that category-effects are very context dependent; an aspect which has been neglected in earlier literature on category-specificity. PACE provides a useful framework in this respect, as it specifies how category-effects are influenced by changes in task and stimulus characteristics.
Psychophysical results from experiments on recognition & categorisation
A firm understanding of how the human visual system recognises and categorises objects is important in order to build a successful cognitive vision system. We have reviewed the relevant literature both on visual object recognition and categorisation (chapter 1). Based on this review and the technical annex of this project we have addressed several topics in a series of psychophysical experiments, focusing on structural aspects of recognition memory, object similarity in the context of categorisation, shape transformations in categorisation, the role of context in recognition and categorisation, and the interplay between object motion and shape for categorisation decisions (chapter 2). Based on our psychophysical results we present our view on recognition and categorisation, proposing an integrative framework that serves as a theoretical basis for a computational recognition system grounded in cognitive research (chapter 3).
Familiarity effects on categorization levels of faces and objects
Cognition, 2009
It is well established that faces, in contrast to objects, are categorized as fast or faster at the individual level (e.g., Bill Clinton) than at the basic-level (e.g., human face). This subordinate-shift from basiclevel categorization has been considered an outcome of visual expertise with processing faces. However, in the present study we found that, similar to familiar faces, categorization of individuallyknown familiar towers is also faster at the individual level than at the basic-level in naïve participants. In addition, category-verification of familiar stimuli, at basic and superordinate levels, was slower and less accurate compared to unfamiliar stimuli. Thus, the existence of detailed semantic information, regardless of expertise, can induce a shift in the default level of object categorization from basic to individual level. Moreover, the individually-specific knowledge is not only more easilyretrieved from memory but it might also interfere with accessing more general category information.
Classification in well-defined and ill-defined categories: evidence for common processing strategies
Journal of experimental psychology. General, 1980
Early work in perceptual and conceptual categorization assumed that categories had criterial features and that category membership could be determined by logical rules for the combination of features. More recent theories have assumed that categories have an ill-defined structure and have prosposed probabilistic or global similarity models for the verification of category membership. In the experiments reported here, several models of categorization were compared, using one set of categories having criterial features and another set having an ill-defined structure. Schematic faces were used as exemplars in both cases. Because many models depend on distance in a multidimensional space for their predictions, in Experiment 1 a multidimensional scaling study was performed using the faces of both sets as stimuli, In Experiment 2, subjects learned the category membership of faces for the categories having criterial features. After learning, reaction times for category verification and typ...