The insistence of vision: Why do people look at a salient stimulus when it signals target absence?

Researchers and practitioners across many fields would benefit from the ability to predict human search time in complex visual displays. However, a missing element in our ability to predict search time is our ability to quantify the exogenous attraction of visual objects in terms of their impact on search time. The current work represents an initial step in this direction. We present two experiments using a quadrant search task to investigate how exogenous and endogenous factors influence human visual search. In Experiment 1, we measure the oculomotor capture—or the tendency of a stimulus to elicit a saccade—of a salient quadrant under conditions in which the salient quadrant does not predict target location. Despite the irrelevance of quadrant salience, we find that subjects persist in making saccades towards the salient quadrant at above-chance levels. We then present a Bayesian-based ideal performer model that predicts search time and oculomotor capture when the salient quadrant never contains the search target. Experiment 2 tested the predictions of the ideal performer model and revealed human performance to be in close correspondence with the model. We conclude that, in our speeded search task, the influence of an exogenous attractor on saccades can be quantified in terms of search time costs and, when these costs are considered, both search time and search behaviour reflect a boundedly optimal adaptation to the cost structure of the environment.     

A model of amygdala–hippocampal–prefrontal interaction in fear conditioning and extinction in animals

Empirical research has shown that the amygdala, hippocampus, and ventromedial prefrontal cortex (vmPFC) are involved in fear conditioning. However, the functional contribution of each brain area and the nature of their interactions are not clearly understood. Here, we extend existing neural network models of the functional roles of the hippocampus in classical conditioning to include interactions with the amygdala and prefrontal cortex. We apply the model to fear conditioning, in which animals learn physiological (e.g. heart rate) and behavioral (e.g. freezing) responses to stimuli that have been paired with a highly aversive event (e.g. electrical shock). The key feature of our model is that learning of these conditioned responses in the central nucleus of the amygdala is modulated by two separate processes, one from basolateral amygdala and signaling a positive prediction error, and one from the vmPFC, via the intercalated cells of the amygdala, and signaling a negative prediction error. In addition, we propose that hippocampal input to both vmPFC and basolateral amygdala is essential for contextual modulation of fear acquisition and extinction. The model is sufficient to account for a body of data from various animal fear conditioning paradigms, including acquisition, extinction, reacquisition, and context specificity effects. Consistent with studies on lesioned animals, our model shows that damage to the vmPFC impairs extinction, while damage to the hippocampus impairs extinction in a different context (e.g., a different conditioning chamber from that used in initial training in animal experiments). We also discuss model limitations and predictions, including the effects of number of training trials on fear conditioning.     

AX+, BX- discrimination learning in the fear-potentiated startle paradigm: possible relevance to inhibitory fear learning in extinction

The neural mechanisms of fear suppression most commonly are studied through the use of extinction, a behavioral procedure in which a feared stimulus (i.e., one previously paired with shock) is nonreinforced repeatedly, leading to a reduction or elimination of the fear response. Although extinction is perhaps the most convenient index of fear inhibition, a great deal of behavioral work suggests that postextinction training conditioned stimuli are both excitatory and inhibitory, making it difficult to determine whether a neural manipulation affects inhibition, excitation, or some combination thereof. For this reason we sought to develop a behavioral procedure that would render a stimulus primarily inhibitory while at the same time avoiding some of the issues raised by the traditional conditioned inhibition paradigm, namely second-order conditioning, external inhibition, and configural learning. Using the fear-potentiated startle paradigm, we adapted an AX+, BX- training procedure in which stimuli A and X were presented simultaneously and paired with shock, and stimuli B and X were presented simultaneously in the absence of shock. In testing, high levels of fear-potentiated startle were seen in the presence of A and AX and much lower levels were seen in the presence of B and AB, as would be predicted if stimulus B were a conditioned inhibitor. We believe this method is a viable alternative to the traditional conditioned inhibition training procedure and will be useful for studying the neural mechanisms of fear inhibition.     

Development of the Multidimensional Acculturative Stress Inventory for adults of Mexican origin

The Multidimensional Acculturative Stress Inventory (MASI), a 36-item stress measure that was developed to assess acculturative stress among persons of Mexican origin living in the United States, was tested on a community sample of 174 adults (117 women, 57 men). Principal-components analyses yielded 4 stable and internally consistent factors: Spanish Competency Pressures (7 items), English Competency Pressures (7 items), Pressure to Acculturate (7 items), and Pressure Against Acculturation (4 items). These 4 factors accounted for 64.4% of the variance and correlated in the expected directions with criterion measures of acculturation and/or psychological adjustment. Further reliability and validity testing of the MASI is discussed as well as the utility of this measure in assessing acculturative stress among adults of Mexican origin.     

Accessibility of potential referents following categorical anaphors

In 4 experiments, the authors investigated the accessibility of potential antecedents that were either referents or nonreferents of categorical anaphors using several methodologies. In 2 preliminary experiments, using an immediate probe recognition task, the authors replicated previous findings of inhibition for nonreferents following categorical anaphors. In Experiments 1-3, naming times to nonreferent probes were inhibited, but only at a delay and at the end of the sentence. Eye movements were monitored in Experiment 4, and reading times were found to be slower in end-of-sentence regions following the remention of the nonreferent but not on the nonreferent itself. These results suggest that decreases in nonreferent accessibility are due to postanaphoric processes, such as integrating the nonreferent into the discourse structure, and are not due to more immediate changes in activation occurring as part of the resolution process. Further, some inhibition effects may result from the use of probe tasks that require decisions.     

Psychophysiological reactivity to mental arithmetic stress in black and white normotensive men

Racial differences in physiological responses to a behavioral stressor were examined. Thirty-four Black and 42 White male normotensives 34 to 55 years old (mean age = 43.01 years) performed a mental arithmetic task while blood pressure, heart rate, and skin conductance were recorded. Compared to Whites, Blacks had significantly higher baseline diastolic blood pressure (77.93 mm Hg vs. 73.11 mm Hg) and lower skin conductance levels (11.08 microS vs. 12.25 microS). These effects persisted during performance of the mental arithmetic task. However, when baseline differences were covaried, there were no significant physiological effects associated with the task. Analysis of changes in response levels from baseline revealed a nonsignificant trend for Whites to show greater increases in systolic blood pressure than Blacks. There were no significant race or family history effects. Further, task performance did not influence the outcome. Failure to demonstrate greater cardiovascular reactivity in Blacks and all men with a positive family history of hypertension is discussed with regard to possible "survivor effects" and methodologic limitations.     

Elaborative inferences during reading: do they occur on-line?

Four experiments were conducted to examine the extent to which readers construct elaborative inferences on-line during reading. In Experiment 1, gaze durations were measured while subjects read anaphors to target antecedents that referenced a particular category member either explicitly or implicitly. When the context strongly suggested a particular category member, gaze durations on an anaphor were the same following either an implicit or an explicit antecedent. When the context did not suggest any particular category member, gaze durations were significantly longer following an implicit antecedent. The results confirmed that, with sufficient context, readers will generate a simple elaborative inference on-line. These results were replicated in Experiment 2 in which the materials did not strongly signal the inference but a sentence designed to encourage subjects to infer was included. In Experiment 3, this "demand sentence" was not included, and readers did not appear to construct the targeted inference. The results of Experiment 4 confirmed that once generated, elaborative inferences are stored as part of the long-term-memory representation of a passage.     

Diagnostic judgments as a function of client and therapist race

The purpose of the present investigation was to examine the process of differential evaluation of clients as a function of client and therapist race. It was hypothesized that race of client and therapist would interact, influencing the judgments of client psychopathology, appropriateness for therapy, verbal facility, and likelihood of treatment success despite standardization of the clinical stimuli. Graduate students in clinical psychology and with varying levels of training (i.e., 1 to 5 years) were asked to rate videotaped interviews of clients in which race of the client and level of psychopathology (i.e., normal, neurotic, and psychotic) were systematically varied. There were significant differences in ratings as a function of race of client, race of therapist, and level of psychopathology observed. Black clients were not rated differently on degree of psychopathology but were rated as less verbally skilled and less appropriate for treatment but more likely to benefit from treatment than white clients. Contrary to expectations, white therapists tended to underrate the pathology of black clients. On the other hand, black therapists tended to overrate the pathology of white clients and made mixed judgments of black clients. The implications of these findings are discussed.This study was supported in part by NIMH Research Centers in Minority Institutions (RCMI) Grant G12RR03206-2.     

Actions speak louder

Case material is presented from three analyses in which dramatic, unexpected movements by patients on the couch dominated the analytic hours for long periods of time. The psychoanalytic literature pertinent to this area of acting in is reviewed, and some formulations regarding the shift from verbalization to motor behavior are presented. These center on the proposition that the patients had identified with aggressor parents who regarded actions, not words, as the ultimate conveyers of reality. The analyst's use of countertransference responses as clues to the understanding of the actions is discussed.