Influence of animation on dynamical judgments.

The motions of objects in the environment reflect underlying dynamical constraints and regularities. The conditions under which people are sensitive to natural dynamics are considered. In particular, the article considers what determines whether observers can distinguish canonical and anomalous dynamics when viewing ongoing events. The extent to which such perceptual appreciations are integrated with and influence common-sense reasoning about mechanical events is examined. It is concluded that animation evokes accurate dynamical intuitions when there is only 1 dimension of information that is of dynamical relevance. This advantage is lost when the observed motion reflects higher dimension dynamics or when the kinematic information is removed or degraded.     

Observers’ sensitivity to dynamic anomalies in collisions

The present study examined observers’ ability to discriminate canonical and dynamically anomalous collisions that were presented in either frictionless or frictional systems. Whereas previous research has provided qualitative demonstrations that dynamic information can be extracted from visual events, the current study provides a parametric assessment of observers’ sensitivity to dynamic invariants. Our findings indicate that observers are competent when viewing both familiar, terrestrial (frictional) systems and unfamiliar but computationally simpler, 0-G (frictionless) systems. Thus, our sensitivity to these dynamic invariants in visual events is robust in natural systems whose dynamic properties differ from those of the environment in which we evolved and developed.     

Multidimensional assessment of depression

A brief version of the Multiscore Depression Inventory was evaluated. Good coefficient alpha and test-retest reliabilities were obtained for the total score and the subscales. Two factor analyses were reported which appear to justify the use of a multiscore approach for at least 8 of the 9 subscales: helplessness, energy level, guilt, social introversion, cognitive difficulty, irritability, pessimism, and low self-esteem. Sad mood apparently overlapped with energy level on one analysis (replicating findings with the 118-item Multiscore Depression Inventory), and with self-esteem on the second analysis. Normative data are provided on diverse samples totaling 849 subjects.     

Directed forgetting in pigeons resulting from the reallocation of memory-maintaining processes on forget-cue trials

When procedural artifacts are controlled, it has been difficult to demonstrate directed forgetting in pigeons. However, previous research with pigeons has not allowed for the reallocation of working memory (from forget items to remember items) on forget-cued trials as is possible in human directed forgetting experiments. In the present experiment, directed forgetting was found while controlling for procedural artifacts and allowing the pigeons to reallocate memory resources on forget trials. The results indicate that under these conditions, pigeons have active control over memory processing.     

Rotational and translational components of motion parallax: observers' sensitivity and implications for three-dimensional computer graphics

The motion of objects during motion parallax can be decomposed into 2 observer-relative components: translation and rotation. The depth ratio of objects in the visual field is specified by the inverse ratio of their angular displacement (from translation) or equivalently by the inverse ratio of their rotations. Despite the equal mathematical status of these 2 information sources, it was predicted that observers would be far more sensitive to the translational than rotational component. Such a differential sensitivity is implicitly assumed by the computer graphics technique billboarding, in which 3-dimensional (3-D) objects are drawn as planar forms (i.e., billboards) maintained normal to the line of sight. In 3 experiments, observers were found to be consistently less sensitive to rotational anomalies. The implications of these findings for kinetic depth effect displays and billboarding techniques are discussed.     

A General Measure of Ecological Behavior1

Measurement of ecological behavior across different domains has been troublesome. The present paper argues that the lack of agreement in measuring general ecological behavior may be due to the measurement approach that is commonly used. An ecological behavior measure should be grounded on a probabilistic measurement approach that takes the important features of ecological behavior into consideration. Such a measure was developed in a survey study of 445 members of 2 Swiss transportation associations. Three types of ecological behavior measures were included: a general measure, 3 multiple-item measures, and 3 single-item measures. Results are controlled for social desirability effects. Reliability, internal consistency, and validity scores indicate that a probabilistic measurement approach can measure general ecological behavior accurately and unidimensionally.     

Gravitational acceleration as a cue for absolute size and distance?

When an object’s motion is influenced by gravity, as in the rise and fall of a thrown ball, the vertical component of acceleration is roughly constant at 9.8 m/sec². In principle, an observer could use this information to estimate the absolute size and distance of the object (Saxberg, 1987a; Watson, Banks, von Hofsten, & Royden, 1992). In five experiments, we examined people’s ability to utilize the size and distance information provided by gravitational acceleration. Observers viewed computer simulations of an object rising and falling on a trajectory aligned with the gravitational vector. The simulated objects were balls of different diameters presented across a wide range of simulated distances. Observers were asked to identify the ball that was presented and to estimate its distance. The results showed that observers were much more sensitive to average velocity than to the gravitational acceleration pattern. Likewise, verticality of the motion and visibility of the trajectory’s apex had negligible effects on the accuracy of size and distance judgments.     

Assessment of delusional beliefs during the modification of delusional verbalizations

This study examined the strength of delusional beliefs during the modification of delusional verbalizations of a 51 year-old chronically mentally ill inpatient. The changing-criterion design was used to document the effectiveness of a behavioral treatment package to alter the rate of delusional responses to personal background questions. The results revealed a stepwise decline in the frequency of delusional responses. Generalization effects to novel interviewers were obtained. No changes were obtained on the subject's ratings of delusional beliefs, with the subject assigning ratings of absolute conviction to his beliefs throughout the duration of the study.