Value transfer in a simultaneous discrimination appears to result from within-event Pavlovian conditioning.

When pigeons acquire a simple simultaneous discrimination, some of the value acquired by the S+ transfers to the S–. The mechanism underlying this transfer of value was examined in three experiments. In Experiment 1, pigeons trained on two simultaneous discriminations (A?+?B– and C?+?D–) showed a preference for B over D. This preference was reduced, however, following the devaluation of A. In Experiment 2, when after the same original training, value was given to D, the pigeons' preference for C did not significantly increase. In Experiment 3, when both discriminations involved partial reinforcement (S±), A?+?C– training resulted in a preference for B over D, whereas B?+?D– training resulted in a preference for A over C. Thus, simultaneous discrimination training appears to result in bidirectional within-event conditioning involving the S+ and S–. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interactions of contact, odor cues, and androgens in strange-male-induced early pregnancy disruptions in mice (Mus musculus).

Novel males can disrupt early pregnancy in female house mice (Mus musculus). In Experiment 1, exposure to novel males disrupted pregnancy, but exposure to male urine did not. In Experiment 2, urine from male or female mice or rats painted on females' noses did not influence pregnancy. In Experiment 3, the conjunction of urine painted on female's noses and vulval stimulation did not affect pregnancy more than water with similar stimulation. In Experiment 4, males housed above females were separated from them by a wire mesh grid; intact males disrupted pregnancy, but castrated ones did not. In Experiment 5, such housing of castrated males or ovariectomized females produced a strong disruption of pregnancy if the stimulus animal was given testosterone but not if it was given oil injections. In Experiment 6, transfers of odorous emissions failed to disrupt pregnancy. Contact and androgen activity are necessary for strange males to disrupt pregnancy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatiotemporal Segregation in Visual Search: Evidence From Parietal Lesions.

The mechanisms underlying segmentation and selection of visual stimuli over time were investigated in patients with posterior parietal damage. In a modified visual search task, a preview of old objects preceded search of a new set for a target while the old items remained. In Experiment 1, control participants ignored old and prioritized new items, but patients had severe difficulties finding the target (especially on the contralesional side). In Experiment 2, simplified displays yielded analogous results, ruling out search ease as a crucial factor in poor preview search. In Experiment 3, outlines around distractor groups (to aid segmentation) improved conjunction but not preview search, suggesting a specific deficit in spatiotemporal segmentation. Experiment 4 ruled out spatial disengagement problems as a factor. The data emphasize the role of spatiotemporal segmentation cues in preview search and the parietal lobe in the role of these cues to prioritize search of new stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contextual effects in conditioning, latent inhibition, and habituation: Associative and retrieval functions of contextual cues.

Rats were used as subjects in four experiments to investigate the transfer of learning from one context to another. Subjects received two sessions of training each day, one in each of two different contexts. Experiment 1 showed that the habituation of the unconditioned response to a stimulus presented in one context was left intact when the stimulus was presented in another context, but that latent inhibition was attenuated when preexposure and conditioning phases occurred in different contexts. Experiments 2 and 3 demonstrated that a conditioned response made on the basis of an appetitive reinforcer was diminished when conditioning and testing occurred in different contexts, but that aversive conditioning was not influenced by the context in which testing occurred. In Experiment 4, the presence of an aversive reinforcer during training did not preclude the occurrence of context-specific conditioning on the basis of an appetitive reinforcer. Associative and retrieval-based interpretations of the results are explored. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting transfer performance: A comparison of competing function learning models.

The population of linear experts (POLE) model suggests that function learning and transfer are mediated by activation of a set of prestored linear functions that together approximate the given function (Kalish, Lewandowsky, & Kruschke, 2004). In the extrapolation-association (EXAM) model, an exemplar-based architecture associates trained input values with their paired output values. Transfer incorporates a linear rule-based response mechanism (McDaniel & Busemeyer, 2005). Learners were trained on a functional relationship defined by 2 linear-function segments with mirror slopes. In Experiment 1, 1 segment was densely trained and 1 was sparsely trained; in Experiment 2, both segments were trained equally, but the 2 segments were widely separated. Transfer to new input values was tested. For each model, training performance for each individual participant was fit, and transfer predictions were generated. POLE generally better fit the training data than did EXAM, but EXAM was more accurate at predicting (and fitting) transfer behaviors. It was especially telling that in Experiment 2 the transfer pattern was more consistent with EXAM's but not POLE's predictions, even though the presentation of salient linear segments during training dovetailed with POLE's approach. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does contextual cuing guide the deployment of attention?

Contextual cuing experiments show that when displays are repeated, reaction times to find a target decrease over time even when observers are not aware of the repetition. It has been thought that the context of the display guides attention to the target. The authors tested this hypothesis by comparing the effects of guidance in a standard search task with the effects of contextual cuing. First, in standard search, an improvement in guidance causes search slopes (derived from Reaction Time × Set Size functions) to decrease. In contrast, the authors found that search slopes in contextual cuing did not become more efficient over time (Experiment 1). Second, when guidance was optimal (e.g., in easy feature search), they still found a small but reliable contextual cuing effect (Experiments 2a and 2b), suggesting that other factors, such as response selection, contribute to the effect. Experiment 3 supported this hypothesis by showing that the contextual cuing effect disappeared when the authors added interference to the response selection process. Overall, the data suggest that the relationship between guidance and contextual cuing is weak and that response selection can account for part of the effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of target–distractor relationships in guiding attention and the eyes in visual search.

Current models of visual search assume that visual attention can be guided by tuning attention toward specific feature values (e.g., particular size, color) or by inhibiting the features of the irrelevant nontargets. The present study demonstrates that attention and eye movements can also be guided by a relational specification of how the target differs from the irrelevant distractors (e.g., larger, redder, darker). Guidance by the relational properties of the target governed intertrial priming effects and capture by irrelevant distractors. First, intertrial switch costs occurred only upon reversals of the coarse relationship between target and nontargets, but they did not occur when the target and nontarget features changed such that the relation remained the same. Second, irrelevant distractors captured most strongly when they differed in the correct direction from all other items—despite the fact that they were less similar to the target. This suggests that priming and contingent capture, which have previously been regarded as prime evidence for feature-based selection, are really due to a relational selection mechanism. Here I propose a new relational vector account of guidance, which holds promise to synthesize a wide range of different findings that have previously been attributed to different mechanisms of visual search. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sequential and simultaneous feature positive discriminations: Occasion setting and configural learning in human Pavlovian conditioning.

Using a conditioned suppression preparation, the authors investigated sequential (X→A+/A–) versus simultaneous (XA+/A–) feature positive (FP) discrimination learning in humans. The sequential discrimination was expected to be resolved by means of a Feature X Modulated Target A–US association and the simultaneous discrimination by a feature X–US association. After sequential FP training, extinction of Feature X did not affect discriminative X→A/A responding (Experiment 1), and X transferred its modulatory ability only to new targets, B, that had also been modulated (Experiment 2). This suggests that the sequential FP discrimination indeed resulted in occasion setting. Unlike expected, Feature X Extinction did not affect discriminative XA/A responding after simultaneous FP training (Experiment 3), while at the same time Feature X did show the predicted nonselective transfer to new targets, B (Experiment 4). J. M. Pearce's (1987) configural learning theory can account for most but not all findings of Experiments 3 and 4. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Target location probability effects in visual search: An effect of sequential dependencies.

Target location probability was manipulated in a visual search task. When the target was twice as likely to appear on 1 side of the display as the other, manual button-press response times were faster (Experiment 1A) and first saccades were more frequently directed (Experiment 1B) to the more probable locations. When the target appeared with equal probability at each location in this search task, performance benefited from repetition of target location in the preceding trials (Experiment 2). When the trial sequence was constrained so that target location did not repeat within a series of 4 trials, there was no longer an advantage for more probable locations (Experiment 3). The authors conclude that the search benefits for more probable locations resulted from short-term target location repetitions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lesions of the bed nucleus of the stria terminalis block sensitization of the acoustic startle reflex produced by repeated stress, but not fear-potentiated startle

1. The effects of lesions of the bed nucleus of the stria terminalis (BST) on the acquisition of conditioned fear were examined. In Experiment 1, BST lesions did not block acquisition of fear-potentiated startle to an explicit visual conditioned stimulus (CS) over 20 days of training. However, BST lesions blocked a gradual elevation in baseline startle also seen over the course of training. 2. The gradual increase in baseline startle was replicated in Experiment 2 without the presence of an explicit CS, using unoperated subjects. Experiment 2 showed that the elevation was due to repetitive exposure to shock, because unshocked control subjects did not show any elevation over sessions. 3. In Experiment 3, lesions of the BST did not disrupt rapid sensitization of the startle reflex by footshock, showing that different neural substrates underlie sensitization of startle by acute and chronic exposure to footshock. 4. These data indicate that the BST, despite its anatomical continuity with the amygdala, is not critically involved in the acquisition of conditioned fear to an explicit CS. Nevertheless, the BST is involved in mediating a stress-induced elevation in the startle reflex. This suggests that the BST and the CeA, which constitute part of the "extended amygdala" have complementary roles in responses to stress.     

Exemplar effects in the context of a categorization rule: Featural and holistic influences.

Brooks and colleagues (S. W. Allen & L. R. Brooks, 1991; G. Regehr & L. R. Brooks, 1993) have shown that the classification of transfer stimuli is influenced by their similarity to training stimuli, even when a perfect classification rule is available. It is argued that the original effect obtained by Brooks and colleagues might have resulted from two potential confounding variables. Once these confounds were controlled, the current authors did not replicate Brooks and colleagues' results in Experiment 1. Exemplar effects appeared in Experiment 2 when transfer stimuli were perceptually more similar to training stimuli than in Experiment 1. In Experiment 3, the authors obtained exemplar effects with separated stimuli, a finding that was not predicted by Brooks and colleagues' model. The authors suggest that a close perceptual match between training and transfer stimuli is necessary for the effect to occur, for both integrated and separated stimuli. The nature of this perceptual match, holistic or featural, is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preview Search and Contextual Cuing.

We investigated the effect of contextual cuing (M. M. Chun & Y. Jiang, 1998) within the preview paradigm (D. G. Watson & G. W. Humphreys, 1997). Contextual cuing was shown with a 10-item letter search but not with more crowded 20-item displays. However, contextual learning did occur in a preview procedure in which 10 preview items were followed by 10 new items. Repeating the new items alone did not generate contextual learning, but repeating the preview items alone did, as long as they had a consistent spatial relation with the target. This was not merely due to the onset of the preview items being associated with the target location. No learning effect took place with a preview of homogeneous items that competed less for selection with new stimuli. The results provide evidence for old items being processed in preview search and providing a context for subsequent search of new items. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related deficits in guided search using cues.

The ability of young and older adults to engage in guided conjunction search was tested in 2 experiments. In the cued condition, a picture of the target was presented before the search. In the noncued condition, there was no picture of the target. In Experiment 1, the cue was presented for 200 ms; the magnitude of the cuing effect (noncued response time - cued response time) was greater for the young than for the older observers. In Experiment 2 (older observers only), the cue duration was doubled, and older observers had a larger magnitude of cuing effect than found in Experiment 1 but not as large as what would be expected under generalized slowing. The results indicated that older observers had difficulty with interpreting the cue and setting search parameters when the target varied across trials. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of part-task training using the backward-transfer technique.

Researchers conducted 2 experiments that used backward transfer to improve the efficiency of part-task training for a desktop flight simulator. In Experiment 1, a part-task group showed positive transfer but did not perform as well as a whole-task group. Backward-transfer analysis indicated that only a subset of the component tasks was critical to the criterion task. In Experiment 2, a part-task training regime that used the critical component tasks was compared with a whole-task regime and a part-task regime composed of noncritical component tasks. Results indicated that the critical part-task regime was as effective as the whole-task regime, validating the utility of the backward-transfer technique. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Estimation strategies and the judgment of event frequency.

Processes underlying judgments of absolute event frequency were investigated in 3 experiments. In all 3, word pairs consisting of a target (a category label, e.g., CITY) and context (a category exemplar, e.g., LONDON) were presented in a different or same-context study list. In the different context condition, each target was paired with a new context on each presentation; in the same-context condition, a target always appeared with the same context. Verbal protocols (Experiment 1) and response times (Experiments 2 and 3) indicate that multiple estimation strategies were used and that strategy selection was related to memory contents. In particular, different-context participants often enumerated, and same-context participants did not. Also, because range information only affected same-context estimates (Experiment 3), it appears that a numerical conversion process was necessary when nonenumeration strategies were used. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of GABA and anxiety in the reconsolidation of conditioned fear.

The current study examined the effects of systemic administration of a GABA agonist [midazolam (MDZ)] and a GABA antagonist (bicuculline) on fear responding after brief CS exposure, a procedure thought to involve memory reconsolidation. Using a contextual fear-conditioning paradigm, rats were initially given two context-shock training trials, followed 24 hrs later by a 90-s context exposure (reactivation), and 24 hrs later by a 3-min context test. In Experiment 1, MDZ (2 mg/kg, i.p.), whereas in Experiment 2, bicuculline (1 mg/kg, i.p.), was administered immediately after reactivation. MDZ reduced conditioned freezing, whereas bicuculline only marginally potentiated conditioned freezing. The MDZ fear disruption effect did not occur in the absence of reactivation, and was evident 10 days after the initial test. Experiment 3 induced high levels of baseline anxiety using the single prolonged stress paradigm, and replicated the essential procedure of Experiment 1. Results indicated that MDZ fear disruption did not differ between high and low anxiety rats. The data suggest the involvement of GABA receptors in reconsolidation processes, and the possible clinical use of MDZ in fear reduction with brief reexposure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contextual cueing in naturalistic scenes: Global and local contexts.

In contextual cueing, the position of a target within a group of distractors is learned over repeated exposure to a display with reference to a few nearby items rather than to the global pattern created by the elements. The authors contrasted the role of global and local contexts for contextual cueing in naturalistic scenes. Experiment 1 showed that learned target positions transfer when local information is altered but not when global information is changed. Experiment 2 showed that scene-target covariation is learned more slowly when local, but not global, information is repeated across trials than when global but not local information is repeated. Thus, in naturalistic scenes, observers are biased to associate target locations with global contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flexible feature-based inhibition in visual search mediates magnified impairments of selection: Evidence from carry-over effects under dynamic preview-search conditions.

Evidence for inhibitory processes in visual search comes from studies using preview conditions, where responses to new targets are delayed if they carry a featural attribute belonging to the old distractor items that are currently being ignored—the negative carry-over effect (Braithwaite, Humphreys, & Hodsoll, 2003). We examined whether inhibition was applied in the same manner across different types of displays or whether the inhibitory weighting applied to different features varied with their utility for the search task. To test this, we present the first empirical investigation of negative carry-over effects under the ecologically valid conditions of dynamic visual search. Experiment 1 investigated preview search using dynamic moving and static displays. Detection was very poor when new targets carried the color of the old distractors, and this negative carry-over effect was significantly exaggerated with moving, compared with static, displays. Experiments 2a and 2b demonstrated that this effect could not be attributed to an increased role of preattentive grouping between new and old items for dynamic displays. Collectively, the findings suggest that feature-based inhibition contributes strongly to preview search through dynamic displays, and this leads to an amplified attentional blindness to new targets. The data specifically indicate that inhibitory processes in search differentially weight color and location in moving and static displays, and that feature-based inhibition may underlie many instances of sustained inattentional blindness in everyday life. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Place and response learning in human virtual navigation: Behavioral measures and gender differences.

Two experiments examined the use of place and response strategies by humans navigating virtual multiple T mazes. In Experiment 1, probe trials revealed that participants commonly used place and response strategies, and place strategies were more frequent early in training, whereas response strategies were more frequent late in training. Compared with women, men learned the correct path through the maze more quickly and developed a more stable route through the maze. In Experiment 2, participants were trained to locate 2 targets. One target required participants to use either a place or response strategy, whereas the other target could be found using either strategy. Accuracy improved faster for place training compared with response training, and women outperformed men in both groups. Probe trials testing transfer of the imposed strategy to the other target found faster transfer for place training than for response training and that women demonstrated faster transfer than men. Accuracy on probe trials was correlated with poor route stability in the place-trained group and with good route stability in the response-trained group, indicating that navigation strategy use may be related to measures of improvement in performance on normal trials. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learned avoidance of flavors signaling reduction in a nutrient.

Food-deprived rats learned to avoid a flavor negatively correlated with access to a rich nutrient, 20% maltodextrin (20M) solution. This avoidance in two-bottle choice tests was produced by training consisting of either an unpaired condition where sessions of unflavored 20M were intermixed with sessions of 2 or 3% maltodextrin (2M or 3M) flavored with salt (Experiment 1) or almond (Experiments 3 and 4) or a differential conditioning procedure where one flavor was mixed with 20M and another with 2M (Experiment 2). Avoidance was counter-conditioned by mixing the target flavor with 20M (Experiment 1), generalized to a neutral context (Experiment 3), and displayed strong resistance to extinction (Experiment 4). The results demonstrated that food avoidance learning can occur in the absence of an aversive unconditioned stimulus and indicated that unpaired control groups and differential conditioning procedures may be misleading in flavor preference learning research when further control conditions are absent. (PsycINFO Database Record (c) 2010 APA, all rights reserved)