Discrimination and matching within and between hues measured by reaction times: some implications for categorical perception and levels of information processing

Summary Same-different reaction times (RTs) were obtained for pairs of color samples ranging perceptually from blue to green. In Experiment 1, observers responded with same if both stimuli in a pair were from the same hue category (i.e., blue-blue or green-green) or different if the two stimuli were from different hue categories (i.e., blue-green or green-blue). RT for same responses was faster for pairs of physically identical stimuli (A-A) than for pairs of physically different stimuli (A-a) belonging to the same hue. RT for different responses was faster for larger physical differences across a boundary between hues (A-B 6 step) than for smaller physical differences (A-B 2 step). Experiment 2 replicated and extended these findings: In one phase observers matched pairs of stimuli as same or different by categorical similarity as in Experiment 1, and in a second phase observers matched the same stimulus pairs, this time by physical similarity. Matching by categorical similarity replicated the pattern of results found in Experiment 1. Matching by physical similarity showed that RTs for different responses were equivalently fast independent of the physical difference between A-B pairs, but were faster for A-B than for A-a comparisons. Further, matching identity was faster under categorical match instructions than under physical match instructions. Results of the two experiments support a model of parallel processing of physical and categorical stimulus information in color perception. Further, these reaction-time data and their implications in color perception (for hues) parallel reaction-time data and their implications in speech perception (for phonemes).     

Sustained attention and the Type A behavior pattern: the effect of daydreaming on performance.

The present study examined the ability of Type A and Type B subjects to sustain attention during a 40-min visual vigilance task. It was predicted that Type A subjects would perform better than Type B subjects and that the performance of both groups would be related to the frequency of daydreams during the vigil. Type A subjects outperformed Type B subjects with regard to perceptual sensitivity (A') and number of signal detections. Although both groups reported an increase in the number of their daydreams as the vigil progressed, Type A subjects reported fewer daydreams during each period of watch than did Type B subjects. In addition, an inverse relationship was found between the number of signal detections and the frequency of daydreams.     

Automaticity and the detection of speech

The development of automatic perceptual responses to speech stimuli was examined. In the first experiment, phoneme-monitoring performance for speech syllables was examined under conditions in which stimulus-to-response mapping and memory load were manipulated. The results indicated that automaticity develops under consistent-mapping conditions. In the second experiment, a dual-task procedure was combined with mapping and selective attention manipulations in order to examine the development of automaticity across single- and multiple-channel conditions. The results indicated that performance under consistently mapped training conditions was interfered with by dividing attention across multiple channels of input. It is concluded that there may be differences in the way that automaticity develops across visual and auditory modalities and that these differences need to be examined more closely.     

Identification of symmetry: Effects of stimulus orientation and head position

It has been argued that the perceptual advantage of symmetry depends upon the essentially symmetrical properties of the visual system. According to this explanation, the ease of identification of symmetries about different axes of orientation should decrease with increasing distance from the vertical: Reaction times to vertical symmetry should be faster than those to diagonal symmetry, which in turn should be faster than those to horizontal symmetry. Previous research demonstrating this pattern of responding employed stimuli with linear axes. In the present study, the subjects viewed tachistoscopically presented symmetrical and asymmetrical dot patterns (which had no explicit axes) in one of three head positions: upright, 45 deg left, and 45 deg right. The subjects’ performance failed to support the structural explanation: Identification of symmetry is equivalently fast for vertical and horizontal; vertical and horizontal show strong advantages over obliques, and this general advantage follows retinal coordinates. Findings are discussed in light of alternative theories of symmetry processing.     

Mishandling the Gift of Life: Noncompliance in Renal Transplant Patients1

Two studies investigating renal transplant patients compliance with their post-transplant medical regimen are presented. Compliance was operationalized as a multidimensional construct incorporating behaviors that represent adherence to the regimen. Study 1 examined the association of noncompliance with clinically significant outcomes and the medical and demographic predictors of noncompliance. Noncompliance was associated with rejection episodes, graft loss, and multiple transplants. The best predictors of noncompliance were medication side effects, age, education, and insurance coverage. Study 2 examined the psychosocial predictors of noncompliance. After age and side-effects complaints, self-efficacy and threat appraisal were the best predictors of compliance. The implications of these results for expectancy-value models of health behaviors (e.g., protection motivation theory; Rogers, 1983) and their ability to predict compliance in patients following long-term regimens are discussed.     

Perceived control,nature of risk information and risk taking. An experimental test of a simple taxonomy of uncertainty

Uncertainty may be categorized along two dimensions: (1) the nature of probabilistic information (i.e. frequency information, about the outcomes of similar situations in the past, versus process information, about the way(s) in which a future loss might occur), and (2) the degree of personal control (i.e. the extent to which an activity's outcomes depend on internal factors (e.g. knowledge, skills) versus external (e.g. chance) factors). The effects of variations in both dimensions on people's risk-taking tendency were experimentally studied. In a computerized task, subjects had to stop a fast-moving symbol before it passed a target line. Success yielded a financial gain, failure led them into a ‘penalty task’ with the possibility of a considerable loss. On each trial subjects chose among 10 risk levels (varying symbol speeds): low levels resulted in small but almost sure gains, high levels yielded larger but less probable gains. Across subgroups of subjects, three penalty task characteristics were varied: (1) the actual loss probability, (2) the external versus internal determination of outcomes, and (3) the available risk information. Major findings were: (a) subjects did not set a lower risk level, but they did appear to be more attentive (i.e. they failed fewer trials) when the actual loss probability was lower; (b) internal outcome determination resulted in more failed trials (lesser caution); (c) subjects ignored frequency information, but were sensitive to process information. Results are discussed in terms of effort allocation for controlling risk during task performance.     

Gender and Ethnic Differences in Obesity-Related Behaviors and Attitudes In a College Sample

This study looked at gender and Black/White differences for a number of variables related to attitudes toward obesity in a sample of 650 college students. The overall stereotypes of overweight persons were both negative and unrelated to subjects' own degree of obesity, although individuals reported that their personal views were less negative than those of others.
Women indicated greater concern with obesity than men in several ways, and the societal stereotype of an overweight woman was seen as more negative than that of an overweight man. Men were more concerned about a date's weight than women, and White women's weight (unlike that of other subgroups) was negatively related to their likelihood and frequency of dating. Although Blacks, particularly Black females, were heavier than Whites, they were more satisfied with their body shape. Black males were less likely than White males to have refused to date someone because of her weight, and Blacks personally considered overweight women to be more attractive, sexier, less ugly, and less sloppy than did Whites. The findings suggest that both gender and ethnicity should be considered when discussing people's attitudes towards obesity and the consequences of such attitudes.     

Infants are trichromats.

Two experiments were conducted to demonstrate that human infants 3 months of age perceive color in a normal, trichromatic manner. In the first experiment, the visual attention of 30 infants was monitored in a habituation-dishabituation paradigm that used spectral and white lights with brightness factors eliminated. Infants discriminated white from monochromatic light in a region of the spectrum (490–500 nm) where color-normal adults can but color-deficient adults cannot. In the second experiment which also used a habituation paradigm, eight infants showed good discrimination between hues in a region of the spectrum (560–580 nm) where color-deficient adults typically show no hue discrimination. Results from these studies of the neutral zone and hue discrimination evidence trichromatic vision in infancy and are discussed in the context of their several clinical, social, and intellectual implications.     

THE EFFECTS OF A SELF-INSTRUCTIONAL PACKAGE ON OVERACTIVE PRESCHOOL BOYS

The effects of a self-instructional package on three overactive preschool boys were investigated using a multiple-baseline design across subjects. Behavioral observations of the three target subjects indicated transfer of training effects from the experimental tasks to the classroom. On-task behaviors increased dramatically concomitant with the introduction of the self-instructional package, and treatment gains were maintained 22.5 weeks after baseline was initiated. In addition, the use of an observer-expectancy control condition gave further credibility to the demonstration of a causal relationship.