Shifts of attention in the identification and discrimination of intensity

Subjects’ ability to resolve stimuli varying in loudness is studied by manipulating task requirements and sequential dependencies in signal presentations. In the first experiment, subjects are required both to identify and to discriminate the same set of 11 randomly presented signals. On the one hand, resolution performance is virtually unchanged under the differing task instructions. On the other hand, large effects on sensitivity are obtained in Experiments 1, 2, and 3 in both identification and discrimination tasks when sequential dependencies are manipulated. The results are interpreted in terms of a shifting attention band in the intensity dimension, as suggested by Luce, Green, and Weber (1976). Preliminary evidence that subjects can voluntarily focus the attention band on a given region of the intensity continuum is obtained.     

Maternal representations during pregnancy and early motherhood

The aim of the present study was to study the maternal representations of pregnant women and mothers in their early postpartum period, by beginning the process of validating the maternal representations questionnaire L'entretien R₁ and by developing a means to assess the content‐free aspects of the representations. Participants were 23 primiparous (first‐time mothers) pregnant women in their fourth to seventh month of pregnancy and 22 primiparous mothers in their early (zero to six months) postpartum period. It was found that the four subscales of L'entretien (self‐as‐mother, self‐as‐person, own‐mother, and partner) produced meaningful results for Turkish subjects. The results were compatible with the idea of integrated representations of self‐as‐person and self‐as‐mother even in the second trimester of their pregnancy and also showed that they could differentiate themselves from their mothers as early as that period. The results revealed no significant differences in the content and content‐free dimensions of the representations of pregnant women and mothers. ©2004 Michigan Association for Infant Mental Health.     

Stimulus-determined discrimination mechanisms for color search

Visual attention can be goal driven, stimulus driven, or a combination of the two. Here we report evidence for an unexpectedly stimulus-driven component of visual search for a target defined by color. Observers demonstrated a surprisingly cost-free ability to incorporate multiple classifiers in search for a target of one color from among distractors of other colors. A target color was presented among distractors that could change from trial to trial (intermixed presentation) or that remained constant across all trials in a block (blocked presentation). For blocked presentation, a single search classifier (a mechanism that segregates the target from distractors in color space) could be adopted, whereas for intermixed presentation different classifiers had to be used when the distractor colors changed. The benefit of blocked presentation was very small, suggesting that the appropriate classifier was determined very quickly in trials for which the classifier changed. The results suggest that the stimulus-driven activation of an appropriate stimulus classifier can be very efficient.     

Maternal representations during pregnancy and early infant-mother interactions

This paper deals with the influence of maternal representations during pregnancy on the subsequent mother-infant relationship and the infant's style of attachment at 1 year of age. Psychoanalytic thinking, beginning with Freud to the most recent contributions, has considered the great importance of the mental dynamics between parents and children to which empirical research according to Bowlby's theoretical perspective has contributed. The current research project was planned in order to study the intergenerational processes. Starting during pregnancy, the woman was interviewed specifically to study maternal representations of herself as a mother and of the future baby. When the child was 1 year old, the style of attachment was studied during the Ainsworth Strange Situation paradigm and, at the same time, the mother was given the Adult Attachment Interview. Case studies are presented to illustrate, from the clinical point of view, the mental dynamics during pregnancy and the influence on the style of attachment of the baby. The clinical implications are discussed especially in terms of the fantasies in pregnancy and their relevance for the subsequent mother-infant relationship.     

Stimulus-determined discrimination mechanisms for color search.

Visual attention can be goal driven, stimulus driven, or a combination of the two. Here we report evidence for an unexpectedly stimulus-driven component of visual search for a target defined by color. Observers demonstrated a surprisingly cost-free ability to incorporate multiple classifiers in search for a target of one color from among distractors of other colors. A target color was presented among distractors that could change from trial to trial (intermixed presentation) or that remained constant across all trials in a block (blocked presentation). For blocked presentation, a single search classifier (a mechanism that segregates the target from distractors in color space) could be adopted, whereas for intermixed presentation different classifiers had to be used when the distractor colors changed. The benefit of blocked presentation was very small, suggesting that the appropriate classifier was determined very quickly in trials for which the classifier changed. The results suggest that the stimulus-driven activation of an appropriate stimulus classifier can be very efficient.     

Thresholds for color discrimination in English and Korean speakers

Categorical perception (CP) is said to occur when a continuum of equally spaced physical changes is perceived as unequally spaced as a function of category membership (Harnad, S. (Ed.) (1987). Psychophysical and cognitive aspects of categorical perception: A critical overview. Cambridge: Cambridge University Press). A common suggestion is that CP for color arises because perception is qualitatively distorted when we learn to categorize a dimension. Contrary to this view, we here report that English speakers show no evidence of lowered discrimination thresholds at the boundaries between blue and green categories even though CP is found at these boundaries in a supra-threshold task. Furthermore, there is no evidence of different discrimination thresholds between individuals from two language groups (English and Korean) who use different color terminology in the blue-green region and have different supra-threshold boundaries. Our participants’ just noticeable difference (JND) thresholds suggest that they retain a smooth continuum of perceptual space that is not warped by stretching at category boundaries or by within-category compression. At least for the domain of color, categorical perception appears to be a categorical, but not a perceptual phenomenon.     

The effect of forced choice on color discrimination

Color discrimination ability was measured at four spectral regions usually named blue, green, yellow, and red. Two methods, temporal forced-choice and phenomenal report, were compared. Data suggest that for color discrimination, phenomenal report is a preferable technique.     

Evolutionary models of color categorization based on discrimination

Specifying the factors that contribute to the universality of color categorization across individuals and cultures is a longstanding and still controversial issue in psychology, linguistics, and anthropology. This article approaches this issue through the simulated evolution of color lexicons. It is shown that the combination of a minimal perceptual psychology of discrimination, simple pragmatic constraints involving communication, and simple learning rules is enough to evolve color-naming systems. Implications of this result for psychological theories of color categorization and the evolution of color-naming systems in human societies are discussed.     

Shifts in Perceived Job Content during Early Employment

Abstract

This paper focuses on shifts in perceived job content among two occupational panels (office technology workers and machine operators) during the first year of their professional career. A shortened version of Fine's Functional Job Analysis is used to measure perceived job content, and at each of the two time stages (i.e. stage T1 and stage T2) the data related to the three domains of People, Things, and Data are optimally scaled and then recoded to a categorical indicator of job content complexity. Shifts in perceived job content are studied by application of log-linear analysis to the multidimensional contingency table obtained by the cross-tabulation of the T1 and the T2 data. The results indicate that there is no general progress or decline in job content activities over time, except for the Things domain. The findings also suggest that there is a substantial symmetry between job progression and degression, and that the bulk of content switches is to adjacent levels of complexity.     

Cognitive discrimination in brain-damaged adults: color vs form preference

The relative preference of color, form, and other dimensions as the basis for discrimination between stimuli has been investigated in a variety of normal and language-impaired populations. In aphasic adults, previous studies have been contradictory, and no studies of non-aphasic, brain-damaged adults have been reported. In this study color vs form preference was examined in 20 left brain-damaged, aphasic adults, 20 right brain-damaged non-aphasic adults, and 20 control subjects. Significant differences were found among all groups, with preference of color over form greatest for left brain-damaged subjects, followed by right-damaged and control subjects.     

Phencyclidine discrimination in the pigeon using color tracking under second-order schedules

Pigeons were trained to track different key colors, depending on whether they had been injected with phencyclidine or saline prior to the session. A second-order schedule was used to generate large numbers of responses prior to the initial food delivery. The procedure offers several advantages over traditional procedures for studying drug discrimination.     

The influence of ultraviolet radiation on the pigeon's color discrimination

Two experiments demonstrated the pigeon's sensitivity to ultraviolet light. In Experiment I, pigeons' responses were reinforced on a multiple schedule with a variable-interval reinforcement schedule in one component and extinction in the other component. Response rates were quite different in the two components where the 520-nm stimuli signalling each component differed only in that one of them contained a 366-nm ultraviolet component. In Experiment II, pigeons were trained to peck one side key when two halves of a split field were of different wavelength and to peck another side key when they were of the same wavelength. Initially, field halves contained both "visible" and ultraviolet components of energy. Discrimination performance improved when the ultraviolet component was removed from one field half. It was argued that the critical change in the stimulus was a color change, rather than a brightness one, or a fluorescence of structures in the pigeon's eye.     

Aphasic patients exhibit a reversal of hemispheric asymmetries in categorical color discrimination

Patients with left hemisphere (LH) or right hemisphere (RH) brain injury due to stroke were tested on a speeded, color discrimination task in which two factors were manipulated: (1) the categorical relationship between the target and the distracters and (2) the visual field in which the target was presented. Similar to controls, the RH patients were faster in detecting targets in the right visual field when the target and distracters had different color names compared to when their names were the same. This effect was absent in the LH patients, consistent with the hypothesis that injury to the left hemisphere handicaps the automatic activation of lexical codes. Moreover, the LH patients showed a reversed effect, such that the advantage of different target-distracter names was now evident for targets in the left visual field. This reversal may suggest a reorganization of the color lexicon in the right hemisphere following left hemisphere brain injury and/or the unmasking of a heightened right hemisphere sensitivity to color categories.     

Stimulus control during conditional discrimination

Pigeons were used to assess stimulus control during the development of a conditional discrimination. The training consisted of three stages. In Stage 1, key pecks were reinforced in the presence of a white line tilted 40 degrees to the right of vertical on a green background and non-reinforced when the same line appeared on a red background. In Stage 2, key pecks were reinforced when a white vertical line appeared on a red background and were non-reinforced in the presence of a 40 degrees slanted line on a red background. In Stage 3, key pecks were reinforced in the presence of the green background regardless of the line tilt, but were differentially reinforced in the presence of the red background (as in Stage 2). Generalization tests were conducted after each stage of training and consisted of five white lines on backgrounds that were green, red, or dark. The effects of the differential reinforcement contingencies on control by line orientation were restricted to the condition in which the red light appeared and resulted in behavioral control that could be characterized as: if red, pay closer attention to line tilt than if not red.     

The effect of appropriate and inappropriate stimulus color on odor discrimination

Color can strongly affect participants' self-report of an odor's qualities. In Experiment 1, we examined whether color influences a more objective measure of odor quality, discrimination. Odor pairs, presented in their appropriate color (e.g., strawberry and cherry in red water), an inappropriate color (e.g., strawberry and cherry in green water), or uncolored water were presented for discrimination. Participants made significantly more errors when odors were discriminated in an inappropriate color. In Experiment 2, the same design was utilized, but with an articulatory suppression task (AST), to examine whether the effect of color was mediated by identification or by a more direct effect on the percept. Here, the AST significantly improved discrimination for the inappropriate color condition, relative to Experiment 1. Although color does affect a more objective measure of odor quality, this is mediated by conceptual, rather than perceptual, means.     

Evidence for acute effects of alcohol and marijuana on color discrimination

Significant dose-related impairments in hue discrimination on the Farnsworth-Munsell 100 hue test were produced by acute doses of alcohol and marijuana. The impairment of color discrimination was predominantly located in the blue region of the color circle and resembles that seen in acquired color vision defects associated with retinal pathology. The transient nature of the reduced color discrimination raises practical problems in tasks which require stable color perception.     

Shifts in attention demands and motor program utilization during motor learning

The relationship between changes in the level of motor program utilization and attention demand during the learning of a motor task was examined. The primary task involved an 86-cm horizontal arm movement which subjects attempted to complete coincident with the end of a 360 degrees sweep of a clock hand. A secondary task performed with the opposite limb required a rapid button press to an auditory probe stimulus presented at various temporal locations within each trial. Control subjects performed either the primary task or the secondary task alone, while experimental subjects performed both tasks in combination. Schmidt's (1972) index of preprogramming was used to measure the level of motor program utilization, while probe reaction time reflected the attention demand of the primary task. There was a stable level of motor programming over four consecutive days of practice (100 trials a day), but a general decrease in attention demand. Implications for an expansion of the concept of the motor program were discussed.