Individuation of visual objects over time

How does an observer decide that a particular object viewed at one time is actually the same object as one viewed at a different time? We explored this question using an experimental task in which an observer views two objects as they simultaneously approach an occluder, disappear behind the occluder, and re-emerge from behind the occluder, having switched paths. In this situation the observer either sees both objects continue straight behind the occluder (called "streaming") or sees them collide with each other and switch directions ("bouncing"). This task has been studied in the literature on motion perception, where interest has centered on manipulating spatiotemporal aspects of the motion paths (e.g. velocity, acceleration). Here we instead focus on featural properties (size, luminance, and shape) of the objects. We studied the way degrees and types of featural dissimilarity between the two objects influence the percept of bouncing vs. streaming. When there is no featural difference, the preference for straight motion paths dominates, and streaming is usually seen. But when featural differences increase, the preponderance of bounce responses increases. That is, subjects prefer the motion trajectory in which each continuously existing individual object trajectory contains minimal featural change. Under this model, the data reveal in detail exactly what magnitudes of each type of featural change subjects implicitly regard as reasonably consistent with a continuously existing object. This suggests a simple mathematical definition of "individual object:" an object is a path through feature-trajectory space that minimizes feature change, or, more succinctly, an object is a geodesic in Mahalanobis feature space.     

Suspensions and detentions in an urban,low-income school: punishment or reward?

Disciplinary records for 3rd through 8th grade students (n = 314) in an inner-city, public school were examined for one school year to assess students' variation in response to discipline. Rates of disciplinary referrals were compared for students who received no detentions or suspensions throughout the year (never group n = 117), students who received one or more detention or suspension in the fall but not in the spring (fall group n = 62), and students who received one or more detention or suspension in the fall and one or more detention or suspension in the spring (fall + spring group n = 75). Results indicated that during the fall, the fall group had nearly equivalent rates of referrals to the fall + spring group; however, the fall group exhibited significantly lower rates of referrals during winter and spring that were nearly equivalent to the never group, as would be expected for a punishment procedure. In contrast, the fall + spring group evidenced increases in referrals across the year, suggesting the possibility that detentions and suspensions were functioning as rewards for this group. The fall + spring group was rated by teachers and peers at mid-year as highly aggressive, lacking social skills, and high on hyperactivity, whereas the fall group and the never group were statistically equivalent on teacher and peer ratings. Implications for mental health programs for urban schools are discussed, especially the need for alternatives to detention and suspension for the subset of students who account for the majority of school discipline.     

Nonverbal measurement of affect: The graphic differential

The measurement of affective meaning (Osgood's three universal factors) is easily accomplished via the semantic differential. However, the verbal nature of this instrument prevents its use with many subject groups in which the measurement of affective meaning would be the most interesting: members of illiterate cultures, verbally damaged individuals such as anomic aphasics and thought-disordered schizophrenics, and children younger than 6 years. For these purposes, the present study describes the development of a nonverbal alternative to the semantic differential and assesses the statistical comparability of scores resulting from the use of the two instruments.This research was supported by Grant NSF GS 2012x to Professors Charles E. Osgood and William H. May.     

Empiricism and linguistics in eighteenth-century Great Britain

This paper aims at specifying the complex links which two major and polemically related 18th-century linguistic theories James Harris' universal grammar in Hermes (1751) and John Horne Tooke's system of etymology in the Diversions of Purley (1786, 1804) bear to empiricism. It describes both the ideologicalethical determining factors of the theories and the epistemological consequences dependent upon their respective philosophical orientation (Harris using classical Greek philosophy against empiricism, Tooke criticizing Locke's semantics along Hobbesian lines). The effects within the linguistic theories are examined through a comparison of the theories of determination which follow from divergent theses concerning abstraction. The analysis proposed in this paper exemplifies once more the historical question of the exact location of the compatibility/incompatibility between empiricist and non-empiricist linguistic theories.     

Buying into the profession: looking at the impact on students of expert videotape demonstrations in counsellor education

From analysing qualitative questionnaires, a group interview, and instructor interviews this study explores the impact of viewing expert demonstration videotapes on students’ learning processes, their identification as counsellors, and understanding of the counselling profession. Commonly, students selectively choose what they see and how they see it. They describe a process of ‘shopping’ and ‘buying into’ specific theoretical, practical, and professional perspectives. Additionally, students give suggestions for the most helpful use of expert demonstration videos in counsellor education. The paper concludes with key questions for further study.     

E-mentoring for youth with special needs: preliminary results.

Recently, a growing number of electronic mentoring (e-mentoring) Web sites have become available that provide vocational and career support. To date, few researchers have addressed the phenomenon of e-mentoring from a socioemotional perspective for populations with special needs. This paper presents a pilot study designed to test and evaluate an e-mentoring intervention program based on mutual self-disclosure and friendship for youth with special needs. Using qualitative methods, the study characterized the e-mentoring process and its contributions to this population. Results provided support for the socioemotional potential of computer-mediated communication for youth with special needs, although some barriers were found. Practical implications for implementing feasible e-mentoring programs for youth with special needs are discussed.     

Foraging and associative learning of visual signals in a parasitic wasp

To cope with environmental variability, animals should gather and use information to reduce uncertainty. In insect parasitoids, associative learning has been widely documented in the context of host foraging. However, despite its potential adaptive value, the insect food searching strategy and cues used to search are poorly understood. In this study, we examined the ability of hymenopteran Venturia canescens females to associate food to a visual cue. To broaden the scope of our results, experiments were performed with both arrhenotokous (sexual) and thelytokous (asexual) individuals. The wasps showed innate attraction for yellow and orange stimuli when presented versus blue stimuli. When trained to associate a food reward with one of the attractive colours (orange), they significantly moved from a distance towards the colour previously associated with food. The choice of the innately preferred colour (yellow) was not modified by associative learning. In the context of food foraging, this study is the first to show associative learning using visual stimuli in a parasitoid and active choice of this colour. This ability gives new insights concerning potential food sources for V. canescens in the field, since flowers are sugar sources, which emit colour signals.     

Measuring Daytime Drowsiness in Nursing Home Residents: The MSLT-NH

A standardized method of assessing daytime drowsiness in frail nursing home residents has not been previously available. We present here the development and test characteristics of an instrument to measure daytime drowsiness in nursing home residents with cognitive and functional impairment, the Multiple Sleep Latency Test-Nursing Home (MSLT-NH). In a standardized manner, the resident is tested three times in one day (at 9 a.m., 11 a.m., and 1 p.m.) to measure the amount of time until the subject falls asleep. The average sleep latency (minutes to fall asleep) is the measure of interest. We tested the MSLT-NH in 95 residents from six community nursing homes in the Los Angeles area (82% of subjects were female; 81% were white, mean age was 86.6 years and mean score on the Mini-Mental State Examination [MMSE] was 9.4). Interrater reliability of the MSLT-NH was quite good (correlations between raters ranged from 0.98 to 0.99; all p values were <.0001). Validity was assessed by comparing MSLT-NH results to simultaneous wrist activity estimation of sleep, and by comparing MSLT-NH findings to results from nighttime sleep estimation by wrist actigraphy the night prior to MSLT-NH. The percent agreement between MSLT-NH and wrist actigraph ranged from 77% to 79% MSLT-NH results were significantly associated with peak duration of nighttime sleep episodes the night prior to testing. The MSLT-NH was also quite acceptable for use in the NH setting. In conclusion, we have developed a promising measure of daytime drowsiness in NH residents. Further testing will help establish whether this test is a clinically useful measure of daytime drowsiness from medications or other conditions in the NH setting.