Decision processes in visual discrimination of line orientation

The contribution of decision factors to the meridional variations in line orientation discrimination was determined for two-alternative forced-choice experimental designs. Using Johnson's (1980) formalization of decision processes in discrimination tasks, we identified three decision factors: the decision rule, memory variance, and criterial noise. In a first experiment, we showed the effect of experimental design on orientation discrimination to be similar at horizontal and oblique standard orientations, indicating that the meridional variations in orientation discrimination were not due to a decision rule anisotropy. In a second experiment, the effect of the interstimulus interval was also found to be similar at both standard orientations, suggesting that the memory variance is isotropic in the orientation domain. The results of two other experiments supported the hypothesis that the meridional variations in orientation discrimination are not due to a criterial noise anisotropy. These different results strongly suggested that the oblique effect in line orientation discrimination is due to sensorial factors rather than to decision factors. Therefore, they further support the hypothesis linking the anisotropy of the preferred orientation distribution of Area 17-S cells (a single physiologically defined class of cells in the primary visual cortex) and the meridional variations in line orientation discrimination.     

Decision factors affecting line orientation judgments in the method of single stimuli

Just noticeable differences in orientation are smaller at principal standard orientations than at oblique standard orientations when they are measured with the method of single stimuli. We determined whether this oblique effect is due to an anisotropy in decision factors. A first series of experiments showed that the subjects compare the stimulus with an internal criterion, and that this decision rule is used at all standard orientations. A second series of experiments determined the influence on the oblique effect of nonsensorial variables related to criterion setting. The results strongly suggest that the effect is not due to a criterial noise anisotropy and that criterion-setting processes are similar at principal and oblique standard orientations. The latter conclusion was also supported by an analysis of the sequential stimulus and response dependencies in this task. Hence, it appears that the oblique effect in line orientation discrimination, when it is measured with the method of single stimuli, is due not to decision factors but to a sensorially based anisotropy.     

Age-related changes in event-related prospective memory performance: a comparison of four prospective memory tasks

The primary purpose of the study was to identify event-based prospective-memory tasks that provide sensitive and reliable tools for assessing effects of normal aging in prospective-memory performance. Four prospective-memory tasks were selected from the literature or were newly developed, with the tasks differing on various dimensions that, for theoretical reasons or based on previous evidence, might determine task sensitivity to age effects on prospective-memory performance: perceptual saliency of prospective target events, frequency of occurrence of prospective target events, complexity of prospective-memory instructions, and provision of feedback after prospective-memory errors. Two of the four tasks yielded large and robust age effects on prospective-memory performance. Correlational analyses suggested that these age effects on prospective-memory performance were mediated, at least in part, by a reduced ability of older adults to maintain prospective intentions in a highly activated state and not by age effects on basic mental speed alone.     

Porn,Peers, and Performing Oral Sex: The Mediating Role of Peer Norms on Pornography’s Influence Regarding Oral Sex

ABSTRACT

The goal of this study was to offer insights into how pornography use might be linked to young adults’ sexual experiences via the mediating role of peer norms (i.e., their perceptions of what same-sex peers do sexually). We focused on oral sex behavior, as it is common in pornography and among young people. Young adults (N = 349; ages 19–30; 54% female) were recruited through a crowdsourcing website. Participants completed an anonymous online survey about the frequency that they observed various sexual behaviors in online pornography, the frequency that they engaged in these behaviors, and their perceptions of the frequency that their peers engaged in these behaviors. Frequency of viewing cunnilingus (men) or fellatio (women) in pornography predicted how often they engaged in oral sex, and this association was mediated by their perceptions of how frequently their peers engaged in oral sex. Peer norms did not mediate how frequently they received oral sex. Findings are discussed in terms of implications for understanding how pornography may relate to young people’s social norms surrounding oral sex and their performance of sexual behaviors, as well as for understanding generally how media consumption relates to adoption of media behaviors through suggesting a social norm.     

Regret and Responsibility Resolved? Evaluating Ordóñez and Connolly's (2000) Conclusions

T. Connolly, L. D. Ordo;aan;atez, and R. Coughlan (1997, Organizational Behavior and Human Decision Processes, 70, 73-85) argued, on the basis of 5 experiments, that regret need not be related to a sense of responsibility for the regretted outcome. We (M. Zeelenberg, W. W. van Dijk, & A. S. R. Manstead, 1998, Organizational Behavior and Human Decision Processes, 74, 254-272) showed in 2 experiments that this conclusion was premature, because it was based on an indirect measure of regret (i.e., overall happiness with the decision outcome). When regret was directly measured, the predicted effects of responsibility were found. L. D. Ordo;aan;atez and T. Connolly (2000, Organizational Behavior and Human Decision Processes, 81, 132-142) replicated our findings in 2 experiments. Based on their findings they arrived at 4 conclusions. In this rejoinder we first discuss Ordó?ez and Connolly's new studies and we then discuss the validity of their 4 conclusions. Copyright 2000 Academic Press.     

Effects of category learning on the stimulus selectivity of macaque inferior temporal neurons

Primates can learn to categorize complex shapes, but as yet it is unclear how this categorization learning affects the representation of shape in visual cortex. Previous studies that have examined the effect of categorization learning on shape representation in the macaque inferior temporal (IT) cortex have produced diverse and conflicting results that are difficult to interpret owing to inadequacies in design. The present study overcomes these issues by recording IT responses before and after categorization learning. We used parameterized shapes that varied along two shape dimensions. Monkeys were extensively trained to categorize the shapes along one of the two dimensions. Unlike previous studies, our paradigm counterbalanced the relevant categorization dimension across animals. We found that categorization learning increased selectivity specifically for the category-relevant stimulus dimension (i.e., an expanded representation of the trained dimension), and that the ratio of within-category response similarities to between-category response similarities increased for the relevant dimension (i.e., category tuning). These small effects were only evident when the learned category-related effects were disentangled from the prelearned stimulus selectivity. These results suggest that shape-categorization learning can induce minor category-related changes in the shape tuning of IT neurons in adults, suggesting that learned, category-related changes in neuronal response mainly occur downstream from IT.     

Haptic after-effect of successively touched curved surfaces

A flat surface is more often judged to be convex after the touching of a concave surface than after the touching of a convex surface. This haptic after-effect increases with the time of contact with the curved surface till it saturates, and it decreases with the time-lapse between the touching of the first surface and the next one. In this paper, the haptic after-effect of two successively touched spherically curved surfaces is investigated. It is found that both surfaces contribute to the after-effect, but the after-effect is not additive. The time course of the after-effect of two successive surfaces can be described by a first-order integrator with a single time constant of about 7 s and an amplitude equal to the difference between the saturation levels of the after-effects of the two surfaces when measured in isolation. The new saturation level is therefore equal to that of the after-effect of the most recently touched surface.     

Comparing the apple of my eye: Parental reactions to academic social comparisons of their elementary school-aged children

The current study examines parents’ reactions to making social comparisons of their children on school-related domains. Parents (N = 117; ages 25 to 49; 94% women) of elementary school-age children (ages 5 to 10; 57.3% girls) were recruited online from Facebook parenting groups and several school districts in Atlantic Canada. Participants were randomly assigned to make either an upward, a downward, or a lateral social comparison about their child’s ability in school. Participants reported the time since the event in comparison, their emotional reactions, their evaluations of their child’s ability in the domain, and how important they perceived the domain to be for their child’s future. Domain importance and evaluations of the child’s abilities also were measured prior to making the comparison. Significant differences based on social comparison condition were found for temporal distance, post-comparison domain importance, and post-comparison assessments of the child’s ability in the domain. The effect of social comparison on post-comparison domain importance was not mediated by post-comparison assessments of the child’s ability, suggesting a direct effect of comparisons on perceived domain importance. These findings suggest that the act of social comparison caused parents to reevaluate the importance of the domain of comparison and their child’s abilities in that domain. Implications for parents and educators are discussed.     

Can neuroimaging really tell us what the human brain is doing? The relevance of indirect measures of population activity

Neuroimaging studies using positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) give an indication towards the localization of mental representations and processes in the human brain. It is not clear to what extent such global measures of neuronal activity, pooling across large populations of neurons, can reveal how certain computations are implemented by the neurons in such population ('computational neuroimaging'). Population activity is related tightly to single-cell activity when all neurons in the population have similar response properties. We describe some evidence from single-cell recordings in monkeys that indicates that neurons with similar response properties are not scattered randomly throughout the visual cortex. Notwithstanding this clustering, populations of nearby neurons are still rather heterogeneous, requiring some prudence in deriving single-cell response properties from population activity. The following review of recent neuroimaging studies of the visual system describes to what degree inferences about computations and representations can be drawn from these studies.     

The effect of feature uncertainty on spatial discriminations

Just noticeable differences (JNDs) in orientation and spatial frequency were measured under two conditions. In one condition the subject was cued before stimulus presentation as to the feature to be discriminated on that trial, while in the other condition the subject was cued only after stimulus offset. JNDs were larger in the latter, feature uncertainty, condition. This feature uncertainty effect increased with decreasing stimulus processing time. The results suggest that this feature uncertainty effect is of sensorial origin. They also demonstrate that it is possible for humans to address selectively those mechanisms that are most relevant for a given discrimination task.