Electrophysiological evidence for a shared representational medium for visual images and visual percepts.

Systematic effects of imagery on visual signal detection performance have been used to argue that imagery and the perceptual processing of stimuli interact at some common locus of activity (Farah, 1985). However, such a result is neutral with respect to the question of whether the interaction occurs during modality-specific visual processing of the stimulus. If imagery affects stimulus processing at early, modality-specific stages of stimulus representation, this implies that the shared stimulus representations are visual, whereas if imagery affects stimulus processing only at later, amodal stages of stimulus representation, this implies that imagery involves more abstract, postvisual stimulus representations. To distinguish between these 2 possibilities, we repeated the earlier imagery-perception interaction experiment while recording event-related potentials (ERPs) to stimuli from 16 scalp electrodes. By observing the time course and scalp distribution of the effect of imagery on the ERP to stimuli, we can put constraints on the locus of the shared representations for imagery and perception. An effect of imagery was seen within 200 ms following stimulus presentation, at the latency of the 1st negative component of the visual ERP, localized at the occipital and posterior temporal regions of the scalp, that is, directly over visual cortex. This finding supports the claim that mental images interact with percepts in the visual system proper and hence that mental images are themselves visual representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal integration between visual images and visual percepts.

Using a temporal integration task, subjects in 5 experiments were expected to combine information from temporally separated visual presentations. Evidence from these experiments indicated that perceptual information can be integrated with previously generated and currently maintained visual images to form a representation that contains information from each source. Properties and limitations of this integration process were also explored, including the time required to generated the image, the speed at which percepts were integrated with images, and the capacity of the representation. Implications for theories of visual processing and memory are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Can patients with obsessive-compulsive disorder discriminate between percepts and mental images? A signal detection analysis.

Signal detection analysis was used to test three hypotheses for repetitive thoughts and behaviors characteristic of obsessive-compulsive disorder (OCD). Patients might have (a) low sensitivity for the difference between having seen something or having imagined seeing it, (b) a high criterion for this discrimination, or (c) difficulty associating context with information in memory. Subjects judged viewed words or imagined words and later indicated which were actually seen. Patients with OCD discriminated seen from imaged words significantly better than normal control subjects, as evidenced by higher d′ scores on a recognition memory task. Groups did not differ in response criterion, β, used to decide whether words had been seen or imaged. Implications for the study of OCD from an information-processing perspective are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationship between mental rotation and representational momentum.

Two experiments explored a possible relationship between mental rotation and representational momentum, a task in which participants were asked to remember an object's position following a sequence of images implying motion. Typically, participants misremember the position as distorted forward along the implied trajectory. If representational momentum relies on mental imagery, the magnitude of memory distortion in a representational momentum task should be positively correlated with the rate of mental rotation. As predicted, faster mental rotation rates and larger memory distortions for object position were observed for rotational axes aligned with the viewers' coordinate system. In addition, participants with slower mental rotation rates produced smaller memory distortions in the implied-event task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychophysical evidence for a functional hierarchy of motion processing mechanisms

Current models of motion perception typically describe mechanisms that operate locally to extract direction and speed information. To deal with the movement of self or objects with respect to the environment, higher-level receptive fields are presumably assembled from the outputs of such local analyzers. We find that the apparent speed of gratings viewed through four spatial apertures depends on the interaction of motion directions among the apertures, even when the motion within each aperture is identical except for direction. Specifically, local motion consistent with a global pattern of radial motion appears 32% faster than that consistent with translational or rotational motion. The enhancement of speed is not reflected in detection thresholds and persists in spite of instructions to fixate a single local aperture and ignore the global configuration. We also find that a two-dimensional pattern of motion is necessary to elicit the effect and that motion contrast alone does not produce the enhancement. These results implicate at least two serial stages of motion-information processing: a mechanism to code the local direction and speed of motion, followed by a global mechanism that integrates such signals to represent meaningful patterns of movement, depending on the configuration of the local motions.     

Appraising the threat of illness: A mental representational approach.

Evaluated a mental model illustrating elements that people consider when evaluating the threat represented by a sign of possible illness. 72 undergraduates were told that they tested positively or negatively for a fictitious risk factor for a disease. Ss were told or not told about a preventive treatment for the disease. Results indicate that Ss testing positively for the risk factor, especially Ss uninformed about its treatment, minimized the threat (e.g., by increasing their estimates of the false-positive rate of the test). Applications of the model to actual illness threats and the relation between threat-related judgments and health-related behavior are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychophysical evidence for fast region-based segmentation processes in motion and color

Theories of image segmentation suggest that the human visual system may use two distinct processes to segregate figure from background: a local process that uses local feature contrasts to mark borders of coherent regions and a global process that groups similar features over a larger spatial scale. We performed psychophysical experiments to determine whether and to what extent the global similarity process contributes to image segmentation by motion and color. Our results show that for color, as well as for motion, segmentation occurs first by an integrative process on a coarse spatial scale, demonstrating that for both modalities the global process is faster than one based on local feature contrasts. Segmentation by motion builds up over time, whereas segmentation by color does not, indicating a fundamental difference between the modalities. Our data suggest that segmentation by motion proceeds first via a cooperative linking over space of local motion signals, generating almost immediate perceptual coherence even of physically incoherent signals. This global segmentation process occurs faster than the detection of absolute motion, providing further evidence for the existence of two motion processes with distinct dynamic properties.     

Effects of spatial cuing on luminance detectability: Psychophysical and electrophysiological evidence for early selection.

Three experiments were conducted to determine whether attention-related changes in luminance detectability reflect a modulation of early sensory processing. Exps 1 and 2 used peripheral cues to direct attention and found substantial effects of cue validity on target detectability; these effects were consistent with a sensory-level locus of selection but not with certain memory- or decision-level mechanisms. In Exp 3, event-related brain potentials were recorded in a similar paradigm using central cues, and attention was found to produce changes in sensory-evoked brain activity beginning within the 1st 1 msec of stimulus processing. These changes included both an enhancement of sensory responses to attended stimuli and a suppression of sensory responses to unattended stimuli; the enhancement and suppression effects were isolated to different neural responses, indicating that they may arise from independent attentional mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measuring shared team mental models: A meta-analysis.

Although shared team mental models are believed to be important to team functioning, substantial interstudy differences in the manner in which mental models are operationalized has impeded progress in this area. We use meta-analysis to cumulate 23 independent studies that have empirically examined shared mental models (SMMs) in relation to team process and performance and test three aspects of measurement as potential moderators: elicitation method, structure representation, and representation of emergence. Results indicate the way in which SMMs are measured and represented at the team level of analysis reveal meaningful distinctions in observed relationships. Specifically, shared mental model operationalization impacts the observed relationship between SMMs and team process; importantly, only methods that model the structure or organization of knowledge are predictive of process. Conversely, while the magnitude of the relationship differed across measurement method, SMMs were positively related to team performance regardless of the manner of operationalization. In summary, knowledge structure is predictive of team process, and both knowledge content and structure are predictive of team performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of shared mental models on team process and performance.

The influence of teammates' shared mental models on team processes and performance was tested using 56 undergraduate dyads who "flew" a series of missions on a personal-computer-based flight-combat simulation. The authors both conceptually and empirically distinguished between teammates' task- and team-based mental models and indexed their convergence or "sharedness" using individually completed paired-comparisons matrices analyzed using a network-based algorithm. The results illustrated that both shared-team- and task-based mental models related positively to subsequent team process and performance. Furthermore, team processes fully mediated the relationship between mental model convergence and team effectiveness. Results are discussed in terms of the role of shared cognitions in team effectiveness and the applicability of different interventions designed to achieve such convergence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Frames and images: Sequential effects in mental rotation.

Recent studies have shown that response time in mental rotation increases with the angular deviation between the current and preceding stimuli, suggesting a frame rotation process in which the intrinsic frame of the previous stimulus is brought into congruence with the coordinates of the current stimulus. In contrast, we show that this process involves image rotation in which the present stimulus is brought into alignment with the orientation of the previous stimulus. Such "backward alignment" succeeds only for shape-preserving sequences (i.e., identical stimuli at different orientations). Four experiments show that the backward alignment process (a) competes with the uprighting process typically found in mental rotation, and the response is determined by the process requiring the shortest rotational path; (b) is related to the tendency to repeat the previous response; (c) is insensitive to the position of the vertical; (d) is indifferent to the representation of the stimulus in long term memory; and (e) is different from the process underlying preparation for a stimulus in a specified orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electrophysiological evidence for temporal overlap among contingent mental processes.

A series of studies assessed perceptual-motor transmission of stimulus information by measuring lateralization of movement-related brain potentials in a choice reaction task with no-go trials. When stimuli varied in shape and size, lateralized potentials on no-go trials suggested that easily recognized shape information was used to initiate motor preparation and that this preparation was aborted when size analysis signified that the response should be withheld. This indicates that movement preparation can begin once partial perceptual information about a stimulus becomes available, contrary to an assumption of fully discrete models of information processing. By contrast, when stimuli varied only in size, no evidence for preliminary response preparation was obtained, contrary to an assumption of fully continuous models but consistent with asynchronous discrete coding models (J. Miller, 1982, 1988). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mammillothalamic tracts and representational memory.

The mammillothalamic tracts, which connect the mammillary bodies of the brain stem with the anterior thalamic nuclei of the forebrain, are an integral segment of Papez's circuit and have long been considered to be involved in mediation of emotional aspects of behavior. The present study, with 33 male Long-Evans rats, showed that a complete transection of these tracts substantially impaired Ss' ability to perform discriminations that depended on representational memory but not those that depended on dispositional memory. Partial lesions of the tract had no effect, and the lesion-induced changes in response time were too small to account for the decrease in accuracy of discriminations that depended on memory. No marked alterations in emotional behavior were observed. Recovery of functional representational memory appeared to be experience- rather than time-dependent. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Abortion and mental health: Evaluating the evidence.

The authors evaluated empirical research addressing the relationship between induced abortion and women’s mental health. Two issues were addressed: (a) the relative risks associated with abortion compared with the risks associated with its alternatives and (b) sources of variability in women’s responses following abortion. This article reflects and updates the report of the American Psychological Association Task Force on Mental Health and Abortion (2008). Major methodological problems pervaded most of the research reviewed. The most rigorous studies indicated that within the United States, the relative risk of mental health problems among adult women who have a single, legal, first-trimester abortion of an unwanted pregnancy is no greater than the risk among women who deliver an unwanted pregnancy. Evidence did not support the claim that observed associations between abortion and mental health problems are caused by abortion per se as opposed to other preexisting and co-occurring risk factors. Most adult women who terminate a pregnancy do not experience mental health problems. Some women do, however. It is important that women’s varied experiences of abortion be recognized, validated, and understood. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mental extrapolation and representational momentum for complex implied motions.

A sequence of static displays implying consistent motions of a pattern induces distortions in memory for the last-observed appearance of the pattern. These memory distortions suggest that there is an internal analogue to physical momentum called representational momentum. Two experiments are reported comparing performance on tasks in which observers must remember the final display with those in which they are instructed to extrapolate the implied motions out to the next step in the sequence. In each experiment, the memory shifts were highly correlated with the actual rates at which the implied motions were extrapolated. In addition, the memory shifts were larger when the mental extrapolations occurred along the same directions of implied motion each time. These findings suggest that the memory shifts depend both on the rate at which the mental extrapolations are performed and on how consistently they are performed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychophysical Test for the Independence of Perception and Action.

Research has suggested that perception and action are independent (see M. A. Goodale & A. Haffenden, 1998). The authors used the Ebbinghaus illusion to test this hypothesis in 2 experiments. Verbal reports of perceived size were compared with maximum grip aperture during grasping (Experiment 1) and manual reports of perceived size (Experiment 2). A multidimensional signal detection analysis was used to distinguish among the possible interactions between the two processes in each experiment (H. Kadlec & J. T. Townsend, 1992a, 1992b). In Experiment 1, the percepts were independent, and there were no interactions between processes for verbal and visuomotor responses. In Experiment 2, the percepts associated with verbal and manual reports were independent, but the processes interacted at the levels of the stimulus information and the decision rules used to transform each percept into a response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting intermediate and multiple conclusions in propositional logic inference problems: Further evidence for a mental logic.

This article examines whether a particular mental logic introduced by M. D. S. Braine, B. J. Reiser, and B. Rumain (1984) is a reasonably accurate model of people's logical routines for propositional reasoning. Participants are presented with reasoning problems; to make their reasoning steps explicit, they write down, in order, everything they infer. The inferences predicted by the model are compared with participants' output. Three quarters of participants' responses were predicted, and 85%–90% of the time the output of the model's core inference rules was written down. To predict equally well, L. J. Rips's (1994) mental logic model would need to adopt some of our model's features. The data indicate several problems in the mental models theory and cannot be explained by pragmatic reasoning schemas. Arguments against a mental logic are questioned. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Video as a medium of oral health education for children with mental handicaps

This study assessed the usefulness, appropriateness, and relevance of a video as an oral health education medium for children with mental handicaps and for preschool groups where children with mental handicaps and healthy children are taught together. The evaluated video was designed for children with mental handicaps but was also recommended for integrated groups. Forty children with mental handicaps from four special education classes and two nursery school groups, 151 normal children from 11 nursery school groups, and the teachers of these classes and groups evaluated the material. The assessment of the material's value was based on the teachers' records of their experiences with the material, their records of the children's opinions and discussions about the material, and their records of drawing interviews with the children. Based on the evaluation, it is apparent that, when used by trained teachers, professionally made videos designed for children with mental handicaps can be useful and valuable aids in educating children of different levels of mental and social development about oral health. Integrated groups need videos featuring both children with mental handicaps and normal role models and with a diversity of contents that will interest and challenge both types of audiences.E.     

The medium and the message in mental imagery: A theory.

Describes a computational theory of imagery that posits that visual mental images are transitory data structures that occur in an analog spatial medium. These "surface" representations are generated from more abstract "deep" representations in long-term memory and, once formed, can be operated upon in various ways. The theory is described in terms of detailed claims about the mental structures and processes invoked during imagery. In addition, the philosophical and empirical roots of the present theory are briefly reviewed. Further, arguments and data that have been offered against the theory are critically examined, and none are found damaging. An alternative account of the data that purportedly support the theory is also examined and found deficient in several respects. Finally, the current status of the "analog-propositional" debate is reviewed. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)