A reexamination of two-point induced movement

Duncker’s (1929) two-point induced movement phenomenon was reexamined to determine whether or not, as Duncker reports, the fixated stimulus is the one which is most likely to appear to move when objective stimulus movement is at or below subject-relative threshold. Data are reported indicating this is not the case.     

A two-point visual control model of steering

When steering down a winding road, drivers have been shown to use both near and far regions of the road for guidance during steering. We propose a model of steering that explicitly embodies this idea, using both a 'near point' to maintain a central lane position and a 'far point' to account for the upcoming roadway. Unlike control models that integrate near and far information to compute curvature or more complex features, our model relies solely on one perceptually plausible feature of the near and far points, namely the visual direction to each point. The resulting parsimonious model can be run in simulation within a realistic highway environment to facilitate direct comparison between model and human behavior. Using such simulations, we demonstrate that the proposed two-point model is able to account for four interesting aspects of steering behavior: curve negotiation with occluded visual regions, corrective steering after a lateral drift, lane changing, and individual differences.     

Manifest anxiety and two-point threshold sensitivity.

The present study utilized 27 college students (14 females, 13 males) to investigate the effects of anxiety upon the ability to attend to detail (two-point threshold sensitivity). It was hypothesized that subjects both low and high in anxiety would have a smaller threshold than mild or moderately anxious subjects. A curvilinear correlation of .83 (p less .01) was obtained between anxiety scores and two-point threshold sensitivity. There was no significant difference between mean thresholds for those scoring above or below the median on the anxiety scale. Suggestions for further research are discussed.     

Tactile short-term memory in relation to the two-point threshold

The purpose of the present work was to discover whether there was a relationship between the sensitivity of a body site as measured by the two-point threshold and the degree or rate of forgetting of a location stimulated at that body site. In Experiment I, it was found that the higher the two-point threshold, the greater the distance between two successive points of stimulation erroneonously thought to be identical (12 body sites). In Experiment II, it was found that forgetting over time was greater when the retention interval was filled with movement or other tactile stimulation than when the retention interval was unfilled (six body sites). It was concluded that highly sensitive areas also show the least degree of forgetting as compared with less sensitive sites, but this statement should be qualified in various ways.     

The effect of set on the two-point tactual threshold

This experiment studies the influence of set on the two-point tactual threshold. The two-point limen (critical stimulus) was determined along the mid-longitudinal line of both volar and dorsal surfaces of the right forearms of seven university students. Test-stimuli were selected at 3 mm. steps both up and down from each of the critical stimuli. Each of these test-stimuli was presented separately, the critical stimulus being interpolated 30 times in each test of the series. The proportions of two-point and one-point responses to the critical stimulus were then determined again in a control series. It was found that, as the test-stimulus deviated in the positive direction from the critical stimulus, the proportion of two-point responses to the critical stimulus increased, reached a maximum and then began to decline. A similar rise and fall in one-point responses were found in the opposite direction. The results were explained by Adaptation Level Theory.     

Empirical correlates of common MMPI-2 two-point codes in male psychiatric inpatients

Empirical correlates of common Minnesota Multiphasic Personality Inventory-2 (MMPI-2) 2-point codes were identified for a sample of 1,213 inpatient men. A comprehensive standardized review of the hospital record was undertaken, and clinically relevant demographic, diagnostic, and behavioral information was extracted from intake summaries obtained prior to administration of the MMPI-2. Nonmutually exclusive psychiatric diagnoses found in the sample included substance abuse or dependence, schizophrenia, depression, bipolar affective disorder post-traumatic stress disorder, and other anxiety disorders as well as personality disorders. Subsamples consisting of the five most frequently obtained well-defined 2-point code types were selected, and empirical correlates of each code type were then identified and described. Remarkable consistency was found between the empirical correlates of the code types obtained in this study and the correlates of the same code types described by other investigators 40 years ago.     

MMPI-ER two-point codes of industrially injured Hispanic workers by DSM-III--R diagnosis.

The purpose of this study was to describe the MMPI-ER two-point codes of 492 Hispanic adults who had sustained work-related injuries and who had applied for workers' compensation benefits. More specifically, the focus was on whether there are unique MMPI two-point codes for Hispanic workers with three specific types of DSM-III--R diagnoses--adjustment disorder, anxiety disorder, and major depression. Analysis suggests that psychiatric condition or diagnosis may act as a moderator variable in Hispanic persons' MMPI performance, including MMPI two-point codes.     

A tactile stimulation device for measuring two-point and gap discrimination thresholds in humans

A device to measure two-point-discrimination and gap-discrimination thresholds is described. The apparatus is capable of controlled and reliable delivery of forces up to 42.50 g while determining point of skin contact and subsequent depth of skin indentation during threshold determination. Stimulus delivery is controlled by computer software that deactivates a solenoid, allowing a counterbalanced beam with one of two stimulus wheels mounted on its end to rise and stimulate the skin. Depth of skin indentation is recorded by hardware that monitors the output of a photocell reflecting the position of the beam. The apparatus allows complete computer control of all data acquisition and recording.     

Somatosensory processing in the biological relatives of schizophrenia patients: a signal detection analysis of two-point discrimination

This study examined 2-point discrimination performance in 1 st-degree biological relatives (n = 39) of individuals with schizophrenia and normal adult control participants (n = 30) recruited from the community. They completed an objective 2-point discrimination task, adapted for use with a signal detection approach to permit separation of discriminability (i.e., sensitivity, d') from response bias/ criterion (or motivation, lnbeta). Relatives revealed poorer performance on the d' index compared with controls. The 2 groups did not differ on lnbeta, suggesting a genuine difference in sensitivity but not response bias. The sensitivity deficit might reflect decreased spatial acuity and/or impaired intensity cue processing of tactile stimuli. Poor performance on the d' index was most closely associated with 2 schizotypic features, namely "odd beliefs/magical thinking."     

Comparability of two-point high-point code patterns from original MMPI norms to MMPI-2 norms for the restandardization sample

Using records from the 1,138 males and 1,462 females in the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) restandardization sample (Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989), two-point high-point code patterns generated from the original norms were compared to the patterns that these subjects obtained from the new norms. Although some code patterns proved to be quite stable across both norms, code comparability was generally lower in this community-based sample than was true for the records from samples of psychiatric patients also reported in Butcher et al. (1989). The sources of differences between the original and the new norms were reviewed, and the implications for profile interpretation based on code patterns were pointed out. The differences arising from the use of the MMPI-2 norms are appreciable; they highlight the need for new empirical data on the correlates of coding patterns based on these norms.