Tachistoscopic exposure and masking of real three-dimensional scenes

Although there are many well-known forms of visual cues specifying absolute and relative distance, little is known about how visual space perception develops at small temporal scales. How much time does the visual system require to extract the information in the various absolute and relative distance cues? In this article, we describe a system that may be used to address this issue by presenting brief exposures of real, three-dimensional scenes, followed by a masking stimulus. The system is composed of an electronic shutter (a liquid crystal smart window) for exposing the stimulus scene, and a liquid crystal projector coupled with an electromechanical shutter for presenting the masking stimulus. This system can be used in both full- and reduced-cue viewing conditions, under monocular and binocular viewing, and at distances limited only by the testing space. We describe a configuration that may be used for studying the microgenesis of visual space perception in the context of visually directed walking.     

Context blocking in rat autoshaping: Sign-tracking versus goal-tracking

Prior experience of unsignaled food can interfere with subsequent acquisition by birds of autoshaped key-pecking at a signal light. This has been understood to indicate that unsignaled food results in context conditioning, which blocks subsequent learning about the keylight-food relationship. In the present experiment with rats lever insertion as the conditioned stimulus (CS) preceded sucrose delivery as the unconditioned stimulus (US). Half the rats initially received unsignaled USs in the conditioning context, while the remainder did not. Both lever-presses (sign-tracking) and magazine-entries (goal-tracking) were recorded. Under immediate reinforcement conditions, prior unsignaled US interfered with sign-tracking, but had no effect on goal-tracking. In two further groups, a trace condition prevented development of sign-tracking. In this case, prior context conditioning interfered with goal-tracking. These results suggest that interference with sign-tracking may reflect response competition, while interference with goal-tracking under trace conditions may reflect failure to acquire a CS-US association.     

Positive evidence for Eysenck’s arousal hypothesis: A combined EEG and MRI study with multiple measurement occasions

Eysenck’s arousal hypothesis suggests that introverts have greater cortical activity than extraverts. This prediction was tested in several studies that used the electroencephalogram (EEG) alpha activity to index cortical arousal, but empirical findings are inconsistent. Possibly, external factors of the measurement situation or static factors such as skull thickness may act as nuisance variables on alpha activity and thus mitigate the relation between arousal and extraversion. The aim of the present study was to test the arousal hypothesis with a focus on these methodological issues. Resting EEG was acquired on several occasions of measurement, skull thickness was quantified with anatomical magnetic resonance imaging (MRI), and extraversion was assessed by questionnaire. There was a positive association between alpha activity and extraversion, which was neither affected by external factors nor by skull thickness. This finding is in line with the arousal hypothesis and suggests that external or static factors do not contribute to the inconsistency of empirical findings.     

Behavioral and neuronal attributes of short- and long-term habituation in the crab Chasmagnathus

Investigations using invertebrate species have led to a considerable progress in our understanding of the mechanisms underlying learning and memory. In this review we describe the main behavioral and neuronal findings obtained by studying the habituation of the escape response to a visual danger stimulus in the crab Chasmagnathus granulatus. Massed training with brief intertrial intervals lead to a rapid reduction of the escape response that recovers after a short term. Conversely, few trials of spaced training renders a slower escape reduction that endures for many days. As predicted by Wagner’s associative theory of habituation, long-term habituation in the crab proved to be determined by an association between the contextual environment of the training and the unconditioned stimulus. By performing intracellular recordings in the brain of the intact animal at the same time it was learning, we identified a group of neurons that remarkably reflects the short- and long-term behavioral changes. Thus, the visual memory abilities of crabs, their relatively simple and accessible nervous system, and the recording stability that can be achieved with their neurons provide an opportunity for uncovering neurophysiological and molecular events that occur in identifiable neurons during learning.     

Effects of rodent prefrontal lesions on object-based, visual scene memory

It has been suggested that certain prefrontal areas contribute to a neural circuit that mediates visual object memory. Using a successive go/no-go visual scene discrimination task, object-based long-term memory was assessed in two rodent prefrontal regions. Rewarded trials consisted of a standard scene of four toy objects placed over baited food wells. The objects and their locations composing the standard scene remained constant for the duration of the study. Trials in which one of the standard scene objects was replaced with a novel object were not rewarded. Following the establishment of a significant difference between latency to approach the rewarded standard scene compared to latency to approach non-rewarded scenes, quinolinic acid or control vehicle was infused into either the prelimbic and infralimbic cortices or the anterior cingulate cortex. Following a 1 week recovery period, subjects were retested. Animals with prelimbic/infralimbic cortex lesions displayed a profound and sustained deficit, whereas, animals with anterior cingulate cortex lesions showed a slight initial impairment but eventually recovered. Both lesion groups acquired a simple single object discrimination task as quickly as controls indicating that the deficits on the original scene discrimination task were not due to motivational, response inhibition, or perceptual problems.     

Moral signals, public outrage, and immaterial harms

Public outrage is often triggered by “immaterially” harmful acts (i.e., acts with relatively negligible consequences). A well-known example involves corporate salaries and perks: they generate public outrage yet their financial cost is relatively minor. The present research explains this paradox by appealing to a person-centered approach to moral judgment. Strong moral reactions can occur when relatively harmless acts provide highly diagnostic information about moral character. Studies 1a and 1b first demonstrate dissociation between moral evaluations of persons and their actions—although violence toward a human was viewed as a more blameworthy act than violence toward an animal, the latter was viewed as more revealing of bad moral character. Study 2 then shows that person-centered cues directly influence moral judgments—participants preferred to hire a more expensive CEO when the alternative candidate requested a frivolous perk as part of his compensation package, an effect mediated by the informativeness of his request.     

PRP-paradigm provides evidence for a perceptual origin of the negative compatibility effect

Visual stimuli (primes) that are made invisible by masking can affect motor responses to a subsequent target stimulus. When a prime is followed by a mask which is followed by a target stimulus, an inverse priming effect (or negative compatibility effect) has been found: Responses are slow and frequently incorrect when prime and target stimuli are congruent, but fast and accurate when prime and target stimuli are incongruent. To functionally localize the origins of inverse priming effects, we applied the psychological refractory period (PRP-) paradigm which distinguishes a perceptual level, a central bottleneck, and a level of motor execution. Two dual-task experiments were run with the PRP-paradigm to localize the inverse priming effect relative to the central bottleneck. Together, results of the Effect-Absorption and the Effect-Propagation Procedure suggest that inverse priming effects are generated by perceptual mechanisms. We suggest two perceptual mechanisms as the source of inverse priming effects.     

Probative v. prejudicial value of eyewitness memory research

A commentary is given on Ebbesen and Konecnis (1996) critical review ofeyewitness memory research and their conclusions that expert testimony hasgreater prejudicial than probative value and should not be admissible incourt. Selective attention is given to issues of admissibility, researchprocedures, face validity, voice identification, lineup fairness, showupsand lineups, and common knowledge. It is concluded that Ebbesen andKonecnis review is a necessary contribution to the field of eyewitnessmemory research. However, the psycho-legal conclusions drawn from thisreview appear to reflect a negative predisposition rather than a balancedscientific appraisal of the literature.     

WHEN THE ANTIDOTE IS THE POISON:

Abstract— The theory of ironic processes of mental control holds that both the most and the least desired effects of attempts to control one's own mental states accrue from two processes an intentional operating process (a conscious, effortful search for mental contents that mil produce a desired slate of mind) and an ironic monitoring process (an unconscious, automatic search for mental contents that signal a failure lo produce the desired Mate of mind) Although the monitoring process usually functions just to activate the operating process, during stress distraction, time urgency, or other mental load, the monitor's effects on mind can supersede those of the operator, producing the very state of mind that is least desired An individual's attempts lo gain mental control may thus precipitate the unwanted mental states.     

Time limits and gender differences on paper-and-pencil tests of mental rotation: a meta-analysis

The purpose of this study was to summarize research relevant to the influence of time limits on gender differences in paper-and-pencil tasks of mental rotation by means of a meta-analysis. Thirty-six effect sizes from published and unpublished studies examining the influence of time constraints were retrieved. Results showed that gender differences in mental rotation are significantly larger when the task is administered with time constraints compared to when such constraints are absent. In addition, the magnitude of gender differences was linearly related to the amount of time available for test completion. These findings were not related to the age or the year of birth of participants in the retrieved studies. The results are discussed with regard to their implications for explanations of gender differences in mental rotation and cognitive abilities in general.