Testing a Poisson counter model for visual identification of briefly presented, mutually confusable single stimuli in pure accuracy tasks

The authors propose and test a simple model of the time course of visual identification of briefly presented, mutually confusable single stimuli in pure accuracy tasks. The model implies that during stimulus analysis, tentative categorizations that stimulus i belongs to category j are made at a constant Poisson rate, v(i, j). The analysis is continued until the stimulus disappears, and the overt response is based on the categorization made the greatest number of times. The model was evaluated by Monte Carlo tests of goodness of fit against observed probability distributions of responses in two extensive experiments and also by quantifications of the information loss of the model compared with the observed data by use of information theoretic measures. The model provided a close fit to individual data on identification of digits and an apparently perfect fit to data on identification of Landolt rings.     

Examining punishment at different explanatory levels

Experimental studies on punishment have sometimes been over-interpreted not only for the reasons Guala lists, but also because of a frequent conflation of proximate and ultimate explanatory levels that Guala's review perpetuates. Moreover, for future analyses we may need a clearer classification of different kinds of punishment.     

Auditory habituation in the fetus and neonate: an fMEG study

Habituation – the most basic form of learning – is used to evaluate central nervous system (CNS) maturation and to detect abnormalities in fetal brain development. In the current study, habituation, stimulus specificity and dishabituation of auditory evoked responses were measured in fetuses and newborns using fetal magnetoencephalography (fMEG). An auditory habituation paradigm consisting of 100 trains of five 500 Hz tones, one 750 Hz tone (dishabituator) and two more 500 Hz tones, respectively, were presented to 41 fetuses (gestational age 30–39 weeks) and 22 newborns or babies (age 6–89 days). A response decrement between the first and fifth tones (habituation), an increment between the fifth tone and the dishabituator (stimulus specificity) and an increment between the fifth (last tone before the dishabituator) and seventh tones (first tone after the dishabituator) (dishabituation) were expected. Fetuses showed weak responses to the first tone. However, a significant response decrement between the second and fifth tones (habituation) and a significant increment between the fifth tone and the dishabituator (stimulus specificity) were found. No significant difference was found for dishabituation nor was a developmental trend found at the group level. From the neonatal data, significant values for stimulus specificity were found. Sensory fatigue or adaptation was ruled out as a reason for the response decrement due to the strong reactions to the dishabituator. Taken together, the current study used fMEG to directly show fetal habituation and provides evidence of fetal learning in the last trimester of pregnancy.     

Attentional capture by emotional faces is contingent on attentional control settings

Attentional capture by schematic emotional faces was investigated in two experiments using the flanker task devised by Eriksen and Eriksen (1974). In Experiment 1, participants were presented with a central target (a schematic face that was either positive or negative) flanked by two identical distractors, one on either side (schematic faces that were positive, negative, or neutral). The objective was to identify the central target as quickly as possible. The impact of the flankers depended on their emotional expression. Consistent with a threat advantage hypothesis (negative faces are processed faster and attract more processing resources), responses to positive faces were slower when these were flanked by (response incompatible) negative faces as compared with positive or neutral faces, whereas responses to negative faces were unaffected by the identity of the flankers. Experiment 2 was a standard flanker task with letter stimuli except that the task-neutral flankers were schematic faces that were either positive, negative, or emotionally neutral. In this case, in which faces and emotional expressions were to be ignored, performance seemed entirely unaffected by the faces. This result suggests that attentional capture by emotional faces is contingent on attentional control settings.     

Comprehending narratives containing flashbacks: evidence for temporally organized representations

This study investigated the representations that readers construct for narratives describing a sequence of events. Participants read narratives describing 4 successive events in chronological order (Event 1, Event 2, Event 3, Event 4 [E1, E2, E3, E4] Experiment 1) or in nonchronological order with E1 being mentioned in a flashback (E2, E3, E1, E4; Experiments 2-4). The information about the duration of E2 was manipulated, and the mental accessibility of E1 was tested at the end of a passage. All 4 experiments showed that E1 was less accessible if the text implied that it occurred a relatively long time ago in the described world compared with when it occurred a shorter time ago. This result suggests that readers construct a temporally organized representation even if the text structure does not suggest such an organization.     

Psychophysiologic effects of applied tension on the emotional fainting response to blood and injury

OBJECTIVE: The present study was designed to investigate the psychophysiologic effects of "Applied Tension" (AT) on the emotional fainting response to blood and injury in a controlled experiment. METHOD: Twenty-two persons reporting to generally feel faint or to have fainted at the sight of blood or injury and 22 participants classified as Non-Fainters were randomly allocated to a treatment or control condition. Psychophysiologic responses were continuously monitored while individuals watched a video depicting open-heart surgery and a control film. Prior to the surgery film, participants in the treatment condition were instructed in the use of AT. RESULTS: All participants classified as Fainters showed a diphasic response pattern while watching the surgery film. This response, however, was significantly attenuated in Fainters in the treatment condition. CONCLUSIONS: These results suggest that AT provides an effective treatment strategy for the prevention of fainting responses in persons with a fear of blood and injury.     

Visual attention: Race models for selection from multielement displays

Summary A choice model for partial report from briefly exposed visual displays (Bundesen, Shibuya, & Larsen, 1985) is further investigated and related to a general class of selection models called independent race models. The choice model relates performance to the numbers of targets and distractors in the stimulus display by way of the choice axiom. In race models, the selection process is viewed as a race between items in the choice set toward a state of having been processed in that the first items reaching this state are the ones selected. If items are processed independently and processing times are exponentially distributed, selection occurs strictly in accordance with the choice axiom, so the race model is a choice model. The choice model also seems to work as a good approximation for independent race models based on other gamma distributions than the exponential one.     

Parallel processing in a multifeature whole-report paradigm

Observers given brief exposures of pairs of colored bars and asked to report both the color and the orientation of each bar showed evidence of stochastic independence between reports of the 4 features (2 colors and 2 orientations). The authors also found virtually perfect stochastic independence between reports of colors and directions of motion of pairwise presented circular disks at each of 3 levels of exposure duration that varied unpredictably from trial to trial. Stimulus triples, rather than pairs, yielded more complex results. However, the findings provide strong evidence that the relevant features of the 2-3 stimuli were identified and localized in parallel across the display.