A measurement theory of illusory conjunctions.

Illusory conjunctions refer to the incorrect perceptual combination of correctly perceived features, such as color and shape. Research on the phenomenon has been hampered by the lack of a measurement theory that accounts for guessing features, as well as the incorrect combination of correctly perceived features. Recently, several investigators have suggested using multinomial models as a tool for measuring feature integration. The authors examined the adequacy of these models in 2 experiments by testing whether model parameters reflect changes in stimulus factors. In a third experiment, confidence ratings were used as a tool for testing the model. Multinomial models accurately reflected both variations in stimulus factors and observers' trial-by-trial confidence ratings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cross-modal illusory conjunctions between vision and touch.

Cross-modal illusory conjunctions (ICs) happen when, under conditions of divided attention, felt textures are reported as being seen or vice versa. Experiments provided evidence for these errors, demonstrated that ICs are more frequent if tactile and visual stimuli are in the same hemispace, and showed that ICs still occur under forced-choice conditions but do not occur when attention to the felt texture is increased. Cross-modal ICs were also found in a patient with parietal damage even with relatively long presentations of visual stimuli. The data are consistent with there being cross-modal integration of sensory information, with the modality of origin sometimes being misattributed when attention is constrained. The empirical conclusions from the experiments are supported by formal models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do illusory conjunctions support the feature integration theory? A critical review of theory and findings.

Presents a critical review of the feature integration theory and the studies of A. Treisman and H. Schmidt (see record 1982-07512-001); W. Prinzmetal et al (see record 1986-26854-001); and K. A. Briand and R. M. Klein (see record 1987-23943-001) and suggests that the phenomenon of illusory conjunctions does not support Treisman's theory of feature integration. I propose that the theory is too vague because it does not explicate the processes that glue features into objects and that each of the reviewed studies has suffered from methodological difficulties that leave the data open to alternative interpretations. The only solid demonstration that attention facilitates feature integration is provided by Experiment 3 of Prinzmetal et al.'s study. This finding, however, is irrelevant to the question of whether feature perception and feature integration can or cannot be performed preattentively. It may simply suggest that in addition to its effect on feature perception, attention can also influence feature integration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A model of the formation of illusory conjunctions in the time domain.

The authors present a model to account for the miscombination of features when stimuli are presented using the rapid serial visual presentation (RSVP) technique (illusory conjunctions in the time domain). It explains the distributions of responses through a mixture of trial outcomes. In some trials, attention is successfully focused on the target, whereas in others, the responses are based on partial information. Two experiments are presented that manipulated the mean processing time of the target-defining dimension and of the to-be-reported dimension, respectively. As predicted, the average origin of the responses is delayed when lengthening the target-defining dimension, whereas it is earlier when lengthening the to-be-reported dimension; in the first case the number of correct responses is dramatically reduced, whereas in the second it does not change. The results, a review of other research, and simulations carried out with a formal version of the model are all in close accordance with the predictions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

If it's not there, where is it? Locating illusory conjunctions.

There is evidence that complex objects are decomposed by the visual system into features, such as shape and color. Consistent with this theory is the phenomenon of illusory conjunctions, which occur when features are incorrectly combined to form an illusory object. We analyzed the perceived location of illusory conjunctions to study the roles of color and shape in the location of visual objects. In Experiments 1 and 2, participants located illusory conjunctions about halfway between the veridical locations of the component features. Experiment 3 showed that the distribution of perceived locations was not the mixture of two distributions centered at the 2 feature locations. Experiment 4 replicated these results with an identification task rather than a detection task. We concluded that the locations of illusory conjunctions were not arbitrary but were determined by both constituent shape and color. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Loosening the constraints on illusory conjunctions: Assessing the roles of exposure duration and attention.

Illusory conjunctions are the incorrect combination of correctly perceived features, such as color and shape. They have been found to occur using a brief exposure (under 200 msec) and a dual task designed to divert attention. The present study investigated the roles of exposure duration and attention in obtaining illusory conjunctions. Several mathematical models of the feature integration task were also assessed. Exp 1 tested participants' accuracy at combining features using a long exposure and an attention-diverting task. Exp 2 compared performance with and without the attention-diverting task. The final experiment compared performance using a brief (0.15 sec) and a long (1.5 sec) exposure duration without an attention-diverting task. Neither attention nor exposure duration had a significant effect on feature integration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Illusory" illusory conjunctions: The conjoining of features of visual and imagined stimuli.

The question of whether illusory conjunctions would occur with visual mental imagery was investigated. In 4 experiments, participants were tachistoscopically presented displays of geometrical figures (varying in shape, color, and solidity) flanked by 2 digits. For half of the trials, participants imagined one of the figures in the display. Illusory conjunctions occurred between the features of the physical (cued) and imagined figures, which suggests that imagery influences perception at the level of visual processing at which features are combined. Moreover, the conjunction errors induced by an imagined figure were similar to those induced by a physical figure with the same features. The pattern of errors could not be accounted for by guessing. Together, these findings support the view that there can be correspondence between visual imagery and visual perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A theory of dynamic occluded and illusory object perception.

Humans see whole objects from input fragmented in space and time, yet spatiotemporal object perception is poorly understood. The authors propose the theory of spatiotemporal relatability (STR), which describes the visual information and processes that allow visible fragments revealed at different times and places, due to motion and occlusion, to be assembled into unitary perceived objects. They present a formalization of STR that specifies spatial and temporal relations for object formation. Predictions from the theory regarding conditions that lead to unit formation were tested and confirmed in experiments with dynamic and static, occluded and illusory objects. Moreover, the results support the identity hypothesis of a common process for amodal and modal contour interpolation and provide new evidence regarding the relative efficiency of static and dynamic object formation. STR postulates a mental representation, the dynamic visual icon, that briefly maintains shapes and updates positions of occluded fragments to connect them with visible regions. The theory offers a unified account of interpolation processes for static, dynamic, occluded, and illusory objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural dynamics of form perception: Boundary completion, illusory figures, and neon color spreading.

Describes the use of a real-time visual processing theory to analyze real and illusory contour formation, contour and brightness interactions, neon color spreading, complementary color induction, and filling-in of discounted illuminants and scotomas. The theory also physically interprets and generalizes E. H. Land's (see record 1979-05257-001) retinex theory. These phenomena are traced to adaptive processes that overcome limitations of visual uptake to synthesize informative visual representations of the external world. Two parallel contour-sensitive processes interact to generate the theory's brightness, color, and form estimates. A boundary contour process is sensitive to orientation and amount of contrast but not to direction of contrast in scenic edges. It synthesizes boundaries sensitive to the global configuration of scenic elements. A feature contour process is insensitive to orientation but sensitive to both amount of contrast and to direction of contrast in scenic edges. It triggers a diffusive filling-in of featural quality within perceptual domains whose boundaries are determined by completed boundary contours. The boundary contour process is hypothesized to include cortical interactions initiated by hypercolumns in Area 17 of the visual cortex. The feature contour process is hypothesized to include cortical interactions initiated by the cytochrome oxydase staining blobs in Area 17. Data from striate and prestriate visual cortex experiments are reviewed, and predictions based on these data are tested. (92 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The basis of illusory correlation.

Replies to G. M. Rosen's (see PA, Vol 54:Issue 6) speculation that associative homogeneity of categories of Rorschach percepts produced illusory correlation in the authors' 1969 study. If this were correct, the illusory correlation would still have been demonstrated. Moreover, his speculation could not be correct. Associative homogeneity of a category of percepts could not cause it to be erroneously perceived as correlated with one symptom rather than with another. Associative homogeneity might, or might not, accentuate an otherwise formed illusory correlation. If it did, equating of categories of percepts on associative homogeneity would still have been inappropriate because these percepts were chosen as real-life clinical examples of Rorschach practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stereotypes and retrieval-provoked illusory source recollections.

When expectations and stereotypes are activated at retrieval, they spontaneously create distorted and illusory recollections that are consistent with these expectations. Participants studied doctor (physician)-related and lawyer-related statements that were presented by 2 different people. When informed, on a subsequent source memory test, (i.e., of who presented what) that one of the study sources was actually a doctor and the other source was a lawyer, there was a strong tendency to attribute the test items in a stereotype-consistent manner. In 3 experiments, participants frequently reported recollecting specific details, such as via "remember" judgments, to justify their stereotype-consistent but incorrect responses. These experiments rule out explanations involving either the misattribution of strong familiarity or differences in the bias to making remember responses as accounts for the illusory source attributions. Instead, the illusory recollections are consistent with the notion that recollective experience is manufactured from both the information in the memory trace and information in the retrieval environment, such as an individual's expectations, stereotypes, and general knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual search for features and conjunctions in development.

Visual search performance was examined in 24 7–8 yr olds, 22 9–10 yr olds, 15 11–12 yr olds, and in 10 young adults (aged 23–30 yrs). Color and orientation feature searches and a conjunction search were conducted. Reaction time (RT) showed expected improvements in processing speed with age. Comparisons of RTs on target-present and target-absent trials were consistent with parallel search on the 2 feature conditions and with serial search in the conjunction condition. The RT results indicate that searches for feature arid conjunctions were treated similarly for children and adults. However, the youngest children missed more targets at the largest array sizes, most strikingly in conjunction search. Based on an analysis of speed/accuracy trade-offs, we suggest that low target-distractor discriminability leads to an undersampling of array elements, and is responsible for the high number of misses in the youngest children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Illusory conjunctions inside and outside the focus of attention.

This article addresses 2 questions that arise from the finding (e.g., W. Prinzmetal et al; see record 1986-26854-001) that visual scenes are first parsed into visual features: (a) the accumulation of location information about objects during their recognition and (b) the mechanism for the binding of the visual features. The first 2 experiments demonstrated that when 2 colored letters were presented outside the initial focus of attention, illusory conjunctions between the color of one letter and the shape of the other were formed only if the letters were less than 1° apart. Separation greater than 2° resulted in fewer conjunction errors than expected by chance. Experiments 3 and 4 showed that inside the spread of attention, illusory connections between the 2 letters can occur regardless of the distance between them. In addition, these experiments demonstrated that the span of attention can expand or shrink like a spotlight. The results suggest that features inside the focus of attention are integrated by an expandable focal attention mechanism that conjoins all features that appear inside its focus. Visual features outside the focus of attention may be registered with coarse location information prior to their integration. Alternatively, a quick and imprecise shift of attention to the periphery may lead to illusory conjunctions among adjacent stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Illusory conjunctions of pitch and duration in unfamiliar tone sequences.

In 3 experiments, the authors examined short-term memory for pitch and duration in unfamiliar tone sequences. Participants were presented a target sequence consisting of 2 tones (Experiment 1) or 7 tones (Experiments 2 and 3) and then a probe tone. Participants indicated whether the probe tone matched 1 of the target tones in both pitch and duration. Error rates were relatively low if the probe tone matched 1 of the target tones or if it differed from target tones in pitch, duration, or both. Error rates were remarkably high, however, if the probe tone combined the pitch of 1 target tone with the duration of a different target tone. The results suggest that illusory conjunctions of these dimensions frequently occur. A mathematical model is presented that accounts for the relative contribution of pitch errors, duration errors, and illusory conjunctions of pitch and duration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Affect-simulating effects of colors.

The assumption that S's response to color on the Rorschach is related to affects was tested by presenting Ss with screen projections of various colors (bright red, green, and gray geometric designs) followed by a list of words (devoid of affect-laden items) to which associations were elicited. Several indices of performance (reaction time, recall, and analysis of the content of the associations) were used to test the validity of the hypothesis. Analysis of reaction times showed the most clearcut evidence supporting the hypothesis that color (particularly red and green) would intrude on the association process more than the neutral gray, and red more so than green. The results were discussed in terms of an "intrusion" hypothesis, i.e., the colors disrupting the ongoing thought process. From Psyc Abstracts 36:02:2HG23D. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The visible persistence of illusory contours.

Measured the visible persistence of illusory contours (ICs) in 2 experiments. In Exp 1, persistence was determined among 12 Ss for IC squares presented for 50 msec. Exp 2, with 10 Ss, varied target duration from 50 to 1,000 msec. For the control figures, visible persistence decreased with increasing target duration. However, with the IC targets, persistence increased sharply with increasing target duration and then decreased. Results suggest that the time it takes for the visual system to construct the subjective contour yields an overall increase in persistence, and this ongoing processing can be seen over long target durations. Data support the existence of cortical components of visible persistence. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Generalizing the illusory correlation effect.

We used two experiments to examine the influence of one's own attitude on the perception of group attitudes. In the first experiment, subjects viewed opinion statements, supposedly made by residents of two towns, on the issue of building a local nuclear power station. One town was large and had frequently occurring statements and the other was small with infrequently occurring statements; there was an equal proportion of pro and anti statements in both towns. The prediction that subjects would perceive an illusory correlation between attitude positions similar to their own (self-relevance) and the infrequently cited (distinctive) town was supported for anti subjects only. Subsequent investigation indicated that this was due to the confounding effect of a prior expectation associating small towns with more antinuclear attitudes. Experiment 2 eliminated the variable of town size by informing subjects that towns of equal size had been more heavily or lightly sampled. Consistent with the hypotheses, both pro and anti subjects perceived an illusory correlation between their own attitude and the town providing the smaller sample, this effect increasing with attitude extremity. The consequences of these findings for the generalizability of illusory correlation explanations of stereotyping are discussed. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Illusory conjunctions in the perception of Chinese characters.

A Chinese compound character consists of a radical component and a stem component. When compound characters were represented briefly, Ss often reported seeing illusory recombinations of radicals and stems. A series of 5 experiments suggested that the probability of seeing illusory characters is not under the direct influence of lexicality, pronounceability, or character frequency, but depends on 2 factors: (1) familiarity defined in terms of unit frequency, i.e., the frequency of occurrence of a unit either by itself or as part of a larger unit, and (2) the context-dependent perceptual distinctiveness of the components of a given character. It is suggested that the seemingly unreliable lexicality effect obtained in English studies may be reduced to a familiarity effect, and that what J. L. McClelland and M. C. Mozer (see record 1986-16293-001) referred to as the surround-similarity effect may be better characterized as an effect of perceptual distinctiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and illusory correlation in judgments of co-occurrence.

Examined the influence of aging on illusory correlation in judgments of co-occurrence. Ten older (aged 60–76 yrs) and 10 younger (aged 17–29 yrs) Ss judged the probability of co-occurrence for events associated with preexisting expectancies after receiving nonsalient or salient information about the true probabilities of co-occurrence of the events. Results showed that when current information on event co-occurrence was not salient, preexisting expectancies strongly influenced the judgments of both younger and older Ss. However, when this information was salient, younger Ss' judgments reflected more accurate adjustment to the probabilistic relationships in the information than did older Ss' judgments. This age difference may be related to changes in memory processes that accompany increasing age and to differences in judgment processes necessitated by these changes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory for visual features and conjunctions in schizophrenia.

The visual working memory (WM) storage capacity of patients with schizophrenia was investigated using a change detection paradigm. Participants were presented with 2, 3, 4, or 6 colored bars with testing of both single feature (color, orientation) and feature conjunction conditions. Patients performed significantly worse than controls at all set sizes but demonstrated normal feature binding. Unlike controls, patient WM capacity declined at set size 6 relative to set size 4. Impairments with subcapacity arrays suggest a deficit in task set maintenance: Greater impairment for supercapacity set sizes suggests a deficit in the ability to selectively encode information for WM storage. Thus, the WM impairment in schizophrenia appears to be a consequence of attentional deficits rather than a reduction in storage capacity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)