Topological structure in the perception of apparent motion

Not only translations and rotations, but also intriguing 'plastic deformations' are observed in apparent motion. What kinds of invariants does the visual system depend on during these transformations to determine that two figures of different shapes nevertheless represent the same object? Experiments are reported in which seven pairs of stimuli with topological differences were used. The evidence suggests that topological invariants may be used in the perception of apparent motion. In spite of variations in other factors, such as brightness, spatial frequency, terminators, etc, subjects displayed a strong preference for motion from a central figure to a figure with the same topological invariants. The results emphasize the importance of topological structure in figure perception.     

Of holes and wholes: the perception of surrounded regions.

Fully enclosed regions in a two-dimensional image can often be perceived either as an object in front of a surface or as a hole through a surface. Several experiments were conducted to determine what factors affect perception of holes versus objects. Three types of factors were tested and found to influence this outcome. First, depth factors directly indicate that the enclosed region lies behind its surrounding surface. Second, grouping factors relate the enclosed region to an outer region that is generally perceived as a continuation of the surface seen through the hole. Finally, figural factors indicate whether the enclosed region is to be perceived as figure or ground. Relations among these factors and their implications for perceptual organization are discussed.     

Odour perception: an object-recognition approach

Object recognition is a crucial component of both visual and auditory perception. It is also critical for olfaction. Most odours are composed of 10s or 100s of volatile components, yet they are perceived as unitary perceptual events against a continually shifting olfactory background (i.e. figure-ground segregation). We argue here that this occurs by rapid central adaptation to background odours combined with a pattern-matching system to recognise discrete sets of spatial and temporal olfactory features-an odour object. We present supporting neuropsychological, learning, and developmental evidence and then describe the neural circuitry which underpins this. The vagaries of an object-recognition approach are then discussed, with emphasis on the putative importance of memory, multimodal representations, and top-down processing.     

Accuracy of head orientation perception in triadic situations: experiment in a virtual environment

Research has revealed high accuracy in the perception of gaze in dyadic (sender- receiver) situations. Triadic situations differ from these in that an observer has to report where a sender is looking, not relative to himself. This is more difficult owing to the less favourable position of the observer. The effect of the position of the observer on the accuracy of the identification of the sender's looking direction is relatively unexplored. Here, we investigate this, focusing exclusively on head orientation. We used a virtual environment to ensure good stimulus control. We found a mean angular error close to 5 degrees. A higher observer viewpoint results in more accurate identification. Similarly, a viewpoint with a smaller angle to the sender's midsagittal plane leads to an improvement in identification performance. Also, we found an effect of underestimation of the error in horizontal direction, similar to findings for dyadic situations.     

Categorical perception of morphed objects using a free-naming experiment

Morphed figures entail a dominant and nondominant interpretation. Testing perception of morphed objects using forced-choice methods demonstrates that morphed figures are perceived as their dominant interpretation (“categorical perception”, or CP). Using a more natural free-naming response could reveal whether CP is an effect independent of method. In Experiment 1, therefore, series of morphed figures were tested for CP using free naming. Half of the morph series were identified as CP patterns. In Experiment 2, we used forced choice to investigate CP, resulting in an increase of number of CP series compared to free naming. The overlap between CP series of Experiments 1 and 2 was small, however. Experiment 3 revealed that higher perceptual similarity between the extremes of the series was strongly related to CP for the free-naming method, in contrast to the forced-choice method. We conclude that the observation of CP depends on the intactness of the intrinsic object structure caused by the morphing procedure.     

An experiment on the theory of visual motion perception

Two classes of theories of motion perception were studied: correlation and gradient models (in the sense of D. Marr). Random-dot kinematograms with a shifted square were presented to subjects, and the 80% threshold for detection of correct direction of movement was determined. Correlation models predict scale invariance, that is, a constant shift measured in units of texture elements of the translated pattern in spite of a geometric magnification. This was refuted for all subjects. The increase of the recognizable translation with the area of the translated form was verified except for the patterns with the largest texture elements (8 minutes of arc). This prediction, however, is not very specific for competing theories. Gradient models are not yet fully specified, and they contain some free parameters. They cannot be tested strictly, but there exist reasonable numerical parameter values by which our data can be satisfactorily explained.     

@Preacher_Bot: an experiment in evangelical speech making

This article is an experiment in digital methodology. It applies tools associated with the digital humanities to the study of Protestant evangelicalism in order to ask what digital research methods can offer the study of religion. Beginning with the development of a social media computer program called a Twitter bot designed to mimic evangelical ministers on twitter, the article considers how digital scholarship allows the work scholars produce to mirror more closely the religious worlds they study. Next, the article analyzes the results of the program using text analysis software. In documenting trends in the bot's output, the article highlights how digital research methods can help answer long-standing questions in the field as well as potentially ask new ones. It concludes, The article, then, is both an exploration of contemporary religious cultures and a consideration of new media methods for analyzing them.     

Hazard perception abilities of experienced and novice motorcyclists: An interactive simulator experiment

This study reports an experiment that compared the hazard perception abilities of experienced and novice motorcycle riders using an interactive, closed-loop, simulator. Participants (n = 49) were categorized into four groups: experienced motorcycle riders with full driver licence, inexperienced motorcycle riders with full driver licence, novice motorcycle riders with full driver licence, and novice motorcycle riders with probationary driver licence. The participants were tested on three scenarios, each consisting of eight hazardous events. They were instructed to ride normally, but to respond appropriately to avoid the hazards. Under certain conditions in the simulator, we found that experienced riders (relative to inexperienced or novice riders) crashed less often, received better performance evaluations, and approached hazards at more appropriate speeds. Interestingly, we also found that some novice riders were overconfident in their riding ability. We discuss how this overconfidence might be related to hazard perception.     

The child development consultant: an experiment

The effects of a new type of practitioner in elementary schools—the Child Development Consultant—were evaluated in contrast to the effects of persons carrying out typical functions of the elementary school counselor and social worker. This two-year project shows trends but no significant differences favoring one type of worker over the other. Evidence suggests the value of a pupil services practitioner in a school, and indicates that although such practitioners were prepared informally and relatively briefly, their effects are the same as those who engage in full, formal preparation programs.     

Placebo effects in spider phobia: an eye-tracking experiment

ABSTRACT

Several eye-tracking studies have revealed that spider phobic patients show a typical hypervigilance-avoidance pattern when confronted with images of spiders. The present experiment investigated if this pattern can be changed via placebo treatment. We conducted an eye-tracking experiment with 37 women with spider phobia. They looked at picture pairs (a spider paired with a neutral picture) for 7?s each in a retest design: once with and once without a placebo pill presented along with the verbal suggestion that it can reduce phobic symptoms. The placebo was labelled as Propranolol, a beta-blocker that has been successfully used to treat spider phobia. In the placebo condition, both the fixation count and the dwell time on the spider pictures increased, especially in the second half of the presentation time. This was associated with a slight decrease in self-reported symptom severity. In summary, we were able to show that a placebo was able to positively influence visual avoidance in spider phobia. This effect might help to overcome apprehension about engaging in exposure therapy, which is present in many phobic patients.     

Action embellishment: an intention bias in the perception of success

Na?ve theories of behavior hold that actions are caused by an agent's intentions, and the subsequent success of an action is measured by the satisfaction of those intentions. However, when an action is not as successful as intended, the expected causal link between intention and action may distort perception of the action itself. Four studies found evidence of an intention bias in perceptions of action. Actors perceived actions to be more successful when given a prior choice (e.g., choose between 2 words to type) and also when they felt greater motivation for the action (e.g., hitting pictures of disliked people). When the intent was to fail (e.g., singing poorly), choice led to worse estimates of performance. A final experiment suggested that intention bias works independent from self-enhancement motives. In observing another actor hit pictures of Hillary Clinton and Barack Obama, shots were distorted to match the actor's intentions, even when it opposed personal wishes. Together these studies indicate that judgments of action may be automatically distorted and that these inferences arise from the expected consistency between intention and action in agency.     

A perception experiment with time-critical graphics animation on the World-Wide Web

The World-Wide Web offers a potentially interesting tool to collect data from a large and heterogeneous audience. While questionnaires have become rather common on the Internet, its potential reaches far beyond text processing. In principle, it is possible not only to perform interactive, dynamic experiments on the Web, but also to include graphical animation and time-critical responses, such as reaction times. We implemented a visual motion extrapolation task on the Web using the programming language Java, which can be interpreted by standard Web browsers such as Netscape or Internet Explorer. The data collected with this method turned out to be reliable and differed little from data obtained in a controlled laboratory setting, with the exception of conditions with fixation instruction. Thus, the Web can, generally speaking, be used for data collection of large sample sizes. The strengths and weaknesses of dynamic visual simulation experiments on the Internet are discussed.     

Unconscious perception and reverie: an intersubjective connection*

This paper discusses an intriguing topic for psychoanalysis: the concept of unconscious communication. Beginning with the concept of unconscious perception, it moves on to figurability and culminates with reverie. Auxiliary concepts, such as receptive unconscious, intersubjectivtiy, countertransferrence and empathy, are discussed in order to articulate the conceptual network on which theoretical arguments are based.