The automaticity of perceiving animacy: Goal-directed motion in simple shapes influences visuomotor behavior even when task-irrelevant

Visual processing recovers not only simple features, such as color and shape, but also seemingly higher-level properties, such as animacy. Indeed, even abstract geometric shapes are readily perceived as intentional agents when they move in certain ways, and such percepts can dramatically influence behavior. In the wolfpack effect, for example, subjects maneuver a disc around a display in order to avoid several randomly moving darts. When the darts point toward the disc, subjects (falsely) perceive that the darts are chasing them, and this impairs several types of visuomotor performance. Are such effects reflexive, automatic features of visual processing? Or might they instead arise only as contingent strategies in tasks in which subjects must interact with (and thus focus on the features of) such objects? We explored these questions in an especially direct way—by embedding such displays into the background of a completely independent “foraging” task. Subjects now moved their disc to collect small “food” dots (which appeared sequentially in random locations) as quickly as possible. The darts were task-irrelevant, and subjects were encouraged to ignore them. Nevertheless, foraging was impaired when the randomly moving darts pointed at the subjects’ disc, as compared to control conditions in which they were either oriented orthogonally to the subjects’ disc or pointed at another moving shape—thereby controlling for nonsocial factors. The perception of animacy thus influences downstream visuomotor behavior in an automatic manner, such that subjects cannot completely override the influences of seemingly animate shapes even while attempting to ignore them.     

Generalizing parametric models by introducing trial-by-trial parameter variability: The case of TVA

We identify two biases in the traditional use of Bundesen’s Theory of Visual Attention (TVA) and show that they can be substantially reduced by introducing trial-by-trial variability in the model. We analyze whole and partial report data from a comprehensive empirical study with 347 participants and elaborate on Bayesian model selection theory for quantifying the advantage of trial-by-trial generalization in general. The analysis provides strong evidence of trial-by-trial variation in both the VSTM capacity parameter and perceptual threshold parameter of TVA. On average, the VSTM capacity bias was found to be at least half an item, while the perceptual threshold parameter was found to be underestimated by about 2 ms.     

Flicker-light induced visual phenomena: frequency dependence and specificity of whole percepts and percept features

Flickering light induces visual hallucinations in human observers. Despite a long history of the phenomenon, little is known about the dependence of flicker-induced subjective impressions on the flicker frequency. We investigate this question using Ganzfeld stimulation and an experimental paradigm combining a continuous frequency scan (1–50 Hz) with a focus on re-occurring, whole percepts. On the single-subject level, we find a high degree of frequency stability of percepts. To generalize across subjects, we apply two rating systems, (1) a set of complex percept classes derived from subjects’ reports and (2) an enumeration of elementary percept features, and determine distributions of occurrences over flicker frequency. We observe a stronger frequency specificity for complex percept classes than elementary percept features. Comparing the similarity relations among percept categories to those among frequency profiles, we observe that though percepts are preferentially induced by particular frequencies, the frequency does not unambiguously determine the experienced percept.     

‘Core Knowledges’: a dissociation between spatiotemporal knowledge and contact‐mechanics in a non‐human primate?

Human toddlers demonstrate striking failures when searching for hidden objects that interact with other objects, yet successfully locate hidden objects that do not undergo mechanical interactions. This pattern hints at a developmental dissociation between contact-mechanical and spatiotemporal knowledge. Recent studies suggest that adult non-human primates may exhibit a similar dissociation. Here, I provide the first direct test of this dissociation using a search paradigm with adult rhesus monkeys. Subjects watched as a plum rolled behind one of two opaque barriers. In Experiment 1, subjects had to locate the plum based on the position of a wall that blocked the plum's trajectory. Subjects searched incorrectly, apparently neglecting information about the location of the wall. However, subjects searched correctly in Experiments 2-4 when they were given spatiotemporal information about the plum's movement. Results indicate that adult monkeys use spatiotemporal information, but not contact-mechanical information, to locate hidden objects. This dissociation between contact-mechanical and spatiotemporal knowledge is discussed in light of developmental theories of core knowledge and the literature on object-based attention in human adults.     

Intention and performance when reading aloud: Context is everything

A widely held account asserts that single words are automatically identified in the absence of an intent to process them in the form of identifying a task set, and implementing it. We provide novel evidence that there is no fixed relation between intention and visual word identification. Subjects were randomly cued on a trial-by-trial basis as to whether to read aloud a single target word (Go) or not (No-go). When the Go-No Go probability was 50% (Experiment 1) the effect of stimulus quality (bright vs. dim targets) was the same size as in a separate block of 100% Go trials. In Experiment 2, where the Go-No Go probability was 80% in the cued condition, the stimulus quality effect was smaller than in the block of all Go trials. These results can be understood in terms of Go trial probability moderating whether subjects (i) hold off beginning to process the target until an intention in the form of a Task Set has been implemented, or (ii) begin to identify the target during the time taken to implement a Task Set. The additivity of stimulus quality and cueing conditions in Experiment 1 support the view that target processing only begins when a Task Set is in place, whereas the under-additivity of stimulus quality and cueing condition in Experiment 2 supports the interpretation that target identification can start during the time that a Task Set is being implemented. Taken together with other results, we conclude that there is no fixed relation between an intention and word identification; context is everything.     

Holding an object one is looking at: Kinesthetic information on the object’s distance does not improve visual judgments of its size

Visual judgments of distance are often inaccurate. Nevertheless, information on distance must be procured if retinal image size is to be used to judge an object’s dimensions. In the present study, we examined whether kinesthetic information about an object’s distance—based on the posture of the arm and hand when holding it—influences the object’s perceived size. Subjects were presented with a computer simulation of a cube. This cube’s position was coupled to that of a rod in the subject’s hand. Its size was varied between presentations. Subjects had to judge whether the cube they saw was larger than, smaller than, or the same size as a reference. On some presentations, a small difference was introduced between the positions of the rod and of the simulated cube. When the simulated cube was slightly closer than the rod, subjects judged the cube to be larger. When it was farther away, they judged it to be smaller. We show that these changes in perceived size are due to alterations in the cube’s distance from the subject rather than to kinesthetic information.     

Modeling patterns of probability calibration with random support theory: Diagnosing case-based judgment

We describe four broad characterizations of subjective probability calibration (overconfidence, conservatism, ecologically perfect calibration, and case-based judgment) and show how Random Support Theory (RST) can serve as a tool for representing, evaluating, and discriminating between these perspectives. We present five studies of probability judgment in a simulated stock market setting and analyse the calibration data in terms of RST parameters. The observed pattern of calibration varies with the outcome base rate and cue value diagnosticity, as predicted by case-based judgment. A similar pattern of calibration is found in real-world judgments of experts in various domains. Case-based RST—defined as RST with stable parameter values—provides a parsimonious account of the substantial changes in calibration performance observed across different judgment environments.     

Juvenile domestic pigs (Sus scrofa domestica) use human-given cues in an object choice task

Research on the comprehension of human-given cues by domesticated as well as non-domesticated species has received considerable attention over the last decade. While several species seem to be capable of utilizing these cues, former work with domestic pigs (Sus scrofa domestica) has shown inconclusive results. In this study, we investigated the use of human-given cues in an object choice task by young domestic pigs (N = 17; 7 weeks of age) who had very limited human contact prior to the experiments. Subjects had to choose between two bowls of which only one was baited with a reward. Over the course of five experiments, pigs were able to use proximal and, with some constraints, also distal pointing cues presented in both a dynamic-sustained and in a momentary manner. When the experimenter was pointing from the incorrect bowl towards the correct one, most of the subjects had problems solving the task—indicating that some form of stimulus/local enhancement affected pigs’ decision making. Interestingly, pigs were able to utilize the body and head orientation of a human experimenter to locate the hidden reward but failed to co-orient when head or body orientation of the experimenter was directed into distant space with no bowls present. Control trials ruled out the possibility that other factors (e.g. odour cues) affected subjects’ choice behaviour. Learning during experiments played a minor role and only occurred in three out of twelve test conditions. We conclude that domestic pigs, even at a very young age, are skilful in utilizing various human-given cues in an object choice task—raising the question whether pigs only used stimulus/local enhancement and associative learning processes or whether they were able to comprehend the communicative nature of at least some of these cues.     

How two causes are different from one: The use of (un)conditional information in Simpson's paradox

In a causally complex world, two (or more) factors may simultaneously be potential causes of an effect. To evaluate the causal efficacy of a factor, the alternative factors must be controlled for (or conditionalized on). Subjects judged the causal strength of two potential causes of an effect that covaried with each other, thereby setting up a Simpson's paradox--a situation in which causal judgments should vary widely depending on whether or not they are conditionalized on the alternative potential cause. In Experiments 1 (table format) and 2 (trial-by-trial format), the subjects did conditionalize their judgments for one causal factor on a known alternative cause. The subjects also demonstrated that they knew what information was needed to properly make causal judgments when two potential causes are available. In Experiment 3 (trial-by-trial), those subjects who were not told about the causal mechanism by which the alternative cause operated were less likely to conditionalize on it. However, the more a subject recognized the covariation between the alternative cause and the effect, the more the subject conditionalized on it. Such behavior may arise from the interaction between bottom-up and top-down processing.     

Covariation information,causal questioning,and interpersonal behavior

The effects of covariation information on perceivers' behavior toward a target person were investigated in a face-to-face setting. Subjects observed a female stimulus person behave in an impolite fashion. They were then presented with consensus, consistency, and distinctiveness information, patterned to imply either a person or an entity explanation for the rude behavior. Some subjects immediately completed a measure of their attributions, whereas others did not answer any attribution question. Subjects then interacted with the target person in an interview setting and afterward rated her on several evaluative dimensions. As predicted, the covariation information presented to subjects affected their impressions of the target person and their behavior toward her during the interaction. These effects were consistent across measures when subjects did not answer the attribution question, but appeared only on certain measures when subjects answered the attribution item prior to the interaction. This pattern of findings was interpreted as showing that the attribution question made subjects uncertain about the true cause of the target's rude behavior.     

An adaptive psychophysical method for subject classification

In psychophysical experiments, one’s goal is usually to measure some continuous parameter hypothesized to determine the statistical properties of a subject’s responses. Methods are well developed that adaptively manipulate stimulus characteristics in such a way that the reliability of the parameter estimate is maximized. However, such methods are inapplicable in situations in which the goal is to assign subjects to discrete categories, rather than to measure a continuous parameter. This paper introduces a technique that is directly applicable to efficient categorization and that adaptively manipulates stimulus characteristics in such a way that the information obtained from each trial is maximized. This technique is based on the principle of minimum estimated expected entropy, whereby stimulus parameters on each trial are chosen in order to minimize the estimated expected entropy of the a posteriori probability distribution that expresses how likely a subject is to belong to each of a group of mutually exclusive categories. A sample implementation of the technique—the classification of infant subjects according to their audiograms—is then described and evaluated via computer simulation.     

Binocular single vision achieved by fusion and suppression

The occurrences of fusion and suppression were determined from stereograms which produced two retinal images located at equal distances but in opposite directions from the fovea. Subjects reported whether the dichoptic stimulus appeared single or not, and if single whether it appeared in the center of the visual field. The report of centrality is predicted by the fusion theory of single vision and that of noncentrality by the suppression theory. Experiment 1, with eight subjects, showed that for small disparities perceived singleness was the percept predicted by the fusion theory; for larger disparities, the percepts could sometimes be predicted by the fusion theory and other times by the suppression theory. Experiment 2, with 16 subjects, showed that with larger stimuli the percept predicted by the fusion theory is more likely to occur. Experiment 3, with four subjects, showed that the centrality was reported when the stimuli were presented for 100 msec. This result provided support for our interpretation that the centrality reports in Experiments 1 and 2 were not due to fixation error and suppression.     

Heuristics and biases in diagnostic reasoning: II. Congruence,information, and certainty

Six experiments were carried out to examine possible heuristics and biases in the evaluation of yes-or-no questions for the purpose of hypothesis testing. In some experiments, the prior probability of the hypotheses and the conditional probabilities of the answers given each hypothesis were elicited from the subjects; in other experiments, they were provided. We found the following biases (systematic departures from a normative model), and interviews and justifications suggested that each was the result of a corresponding heuristic: Congruence bias. Subjects overvalued questions that have a high probability of a positive result given the most likely hypothesis. This bias was apparently reduced when alternative hypotheses or probabilities of negative results are explicitly stated. Information bias. Subjects evaluated questions as worth asking even when there is no answer that can change the hypothesis that will be accepted as a basis for action. Certainty bias. Subjects overvalued questions that have the potential to establish, or rule out, one or more hypotheses with 100% probability. These heuristics are explained in terms of the idea that people fail to consider certain arguments against the use of questions that seem initially worth asking, specifically, that a question may not distinguish likely hypotheses or that no answer can change the hypothesis accepted as a basis for action.     

Strategies of information search in causal analysis

Five experiments investigated the relative prevalence of three search patterns that individuals may use in explaining events with multiple possible causes: (1) parallel search—pursue information about all possible causes before making any causal judgments, (2) serial search—clarify the role of one cause before considering any others, (3) truncated search—clarify the role of one cause without proceeding to consider other causes. In Experiments 1, 2, and 3, subjects were told about an event, two or three nonexclusive possible causes of the event, and a fact implicating one of the suggested causes as influencing the event. Subjects were asked for the question whose answer would help them most in explaining the event. In each experiment, subjects preferred to clarify the role of the implicated cause, a pattern congruent with both the serial and truncated search strategies. Results of a fourth experiment indicated that these preferences reflect a truncated rather than a serial search. A final experiment demonstrated that the preference for information about the implicated cause persists even with the opportunity for a more extended search.     

More about linda or conjunctions in context

Abstract

Tversky and Kahneman (1982; 1983) reported that subjects rated the con junction of two events as more likely than one of the component events. This “conjunction effect” is an error in terms of formal probability, where the probability of more happening is always smaller than the probability of less. They explained this effect in terms of a “representativeness” heuristic. This paper focuses on the context of the problem and the suggestions implied by the questions in the task. The three studies reported here provide evidence that context effects and implicit suggestions alter subjects' judgements. Tvenky and Kahneman's models take no account of such factors. Two studies show that when implicit suggestions are reduced, subjects are much less prone to the conjunction “effect”. Subjects take being asked the question “Is person X a Y?”, as providing evidence that X may be Y.     

Temporal aspects of slant and inclination perception.

Linear transformations (shear or scale transformations) of either horizontal or vertical disparity give rise to the percept of slant or inclination. It has been proposed that the percept of slant induced by vertical size disparity, known as Ogle's induced-size effect, and the analogous induced-shear effect, compensate for scale and shear distortions arising from aniseikonia, eccentric viewing, and cyclodisparity. We hypothesised that these linear transformations of vertical disparity are processed more slowly than equivalent transformations of horizontal disparity (horizontal shear and size disparity). We studied the temporal properties of the stereoscopic slant and inclination percepts that arose when subjects viewed stereograms with various combinations of horizontal and vertical size or shear disparities. We found no evidence to support our hypothesis. There were no clear differences in the build-up of percepts of slant or inclination induced by step changes in horizontal size or shear disparity and those induced by step changes in vertical size or shear disparity. Perceived slant and inclination decreased in a similar manner with increasing temporal frequency for modulations of transformations of both horizontal and vertical disparity. Considerable individual differences were found and several subjects experienced slant reversal, particularly with oscillating stimuli. An interesting finding was that perceived slant induced by modulations of dilation disparity was in the direction of the vertical component. This suggests the vertical size disparity mechanism has a higher temporal bandwidth than the horizontal size disparity mechanism. However, conflicting perspective information may play a dominant role in determining the temporal properties of perceived slant and inclination.     

Distinctiveness and the salience of social category memberships: Is there an automatic perceptual bias towards novelty?

It was hypothesized that the effects of novelty on social category membership salience may be mediated by perceivers' current tasks, rather than by an automatic perceptual bias (Taylor and Fiske, 1978). Subjects viewed tape-slide portrayals of mixed-sex groups (1 male—5 females, 2M—4F, 3M—3F, 4M—2F, 5M—1F) under ‘individual’ (focus on one target person) or ‘collective’ (focus on entire stimulus group) task conditions. Results on measures of sex stereotyping strongly supported the hypothesis, indicating that ‘individual’ task subjects tended to maximize stereotyping in the 1M—5F and 5M—1F conditions whilst ‘collective’ subjects did so in the 3M-3F condition. It is concluded that novel category memberships are not automatically prepotent in social perception, and the results are discussed in the context of a functional approach to the salience problem.     

The consequences for memory of imagining in another person’s voice

Subjects listened to and imagined words and then attempted to discriminate words they had heard from words they had imagined. Discrimination was better when subjects imagined themselves saying the words (Experiments 1 and 2) than when subjects imagined the words in the speaker’s voice. Subjects also had more difficulty discriminating imagined from perceived words when they imagined in the speaker’s voice than when they imagined words in a voice other than their own or the speaker’s (Experiment 1). The results are consistent with the idea that reality monitoring is affected by the degree of similarity in sensory characteristics of memories derived from perception and from imagination (Johnson & Raye, 1981).