Two stages in postcategorical filtering and selection

Memory &; Cognition - In a modified Stroop paradigm, Kahneman and Henik (1981) varied the spatial location of incompatible color words in relation to the position of the ink color to be named. A...     

Integrating pictorial information across eye movements

Six experiments are reported dealing with the types of information integrated across eye movements in picture perception. A line drawing of an object was presented in peripheral vision, and subjects made an eye movement to it. During the saccade, the initially presented picture was replaced by another picture that the subject was instructed to name as quickly as possible. The relation between the stimulus on the first fixation and the stimulus on the second fixation was varied. Across the six experiments, there was about 100-130 ms facilitation when the pictures were identical compared with a control condition in which only the target location was specified on the first fixation. This finding clearly implies that information about the first picture facilitated naming the second picture. Changing the size of the picture from one fixation to the next had little effect on naming time. This result is consistent with work on reading and low-level visual processes in indicating that pictorial information is not integrated in a point-by-point manner in an integrated visual buffer. Moreover, only about 50 ms of the facilitation for identical pictures could be attributed to the pictures having the same name. When the pictures represented the same concept (e.g., two different pictures of a horse), there was a 90-ms facilitation effect that could have been the result of either the visual or conceptual similarity of the pictures. However, when the pictures had different names, only visual similarity produced facilitation. Moreover, when the pictures had different names, there appeared to be inhibition from the competing names. The results of all six experiments are consistent with a model in which the activation of both the visual features and the name of the picture seen on the first fixation survive the saccade and combine with the information extracted on the second fixation to produce identification and naming of the second picture.     

How normal and retarded individuals monitor and regulate speed and accuracy of responding in serial choice tasks

These experiments investigate whether or not differences in the way that retarded and nonretarded individuals monitor and regulate speed and accuracy of responding contribute to the slower and more variable performance of retarded subjects on choice reaction time (RT) tasks. Rabbitt (1979, 1981) suggested that efficient choice RT performance is mediated by subjects tracking increasingly faster RT bands on successive trials until, by making and recognizing errors, they discover those very fast RT levels that should be avoided and those safe bands, just above typical error levels, that should be tracked. Experiments 1A and 1B established that most retarded subjects detect their errors as efficiently as nonretarded controls, a finding that excludes the possibility that retarded subjects do not monitor accuracy efficiently but achieve comparable levels of accuracy by consistently responding within very slow RT bands that minimize likelihood of errors. Experiment 2 showed that while a qualitatively similar trial-by-trial tracking mechanism mediates the performance of both groups, retarded subjects are less efficient at constraining RTs within very fast, but safe, bands. Increasing error probabilities at longer RTs suggest that momentary fluctuations in stimulus discriminability and/or attention are factors affecting RT variability in retarded subjects. The RT patterns for various sequences of correct responses initiated and terminated by errors suggest that the effective past experience (EPEX) guiding trial-by-trial RT adjustments of retarded subjects is short and inadequate, and it was argued that this can account for much of the remaining RT variability contributing to retarded-nonretarded differences. Not only does a short EPEX increase variability by giving rise to long error-free sequences of slower than average RT but also, when combined with occasional specified random fluctuations, it suggests why retarded subjects can achieve, but not sustain, RT levels maintained by nonretarded subjects.     

Uncontrollable shock proactively increases sensitivity to response-reinforcer independence in rats

Learned helplessness theory predicts that animals exposed to inescapable shock acquire an expectancy of response-reinforcer independence, which proactively interferes with learning of response-reinforcer dependence. The theory also predicts that this expectancy can increase sensitivity to subsequent instances of response-reinforcer independence. These experiments test the latter prediction in a paradigm that minimizes the confounding effects of shock-induced activity deficits. Rats were trained to respond for food, then given either escapable, inescapable, or no shock. Subsequently, they received two sessions of response-contingent food followed by sessions of noncontingent food deliveries. During this phase, inescapably shocked animals decreased responding faster than did controls. Experiment 2 replicated this finding with a different schedule of food delivery and a procedure that more directly minimized the possibility that the outcome is due to either direct or indirect shock-induced activity changes. These results support the prediction that uncontrollable aversive events can increase an animal's sensitivity to noncontingent response-reinforcer relationships.     

The role of the accessory and main olfactory systems in maternal behavior of the primiparous rat

The objective of this study was to analyze the respective roles of the main and accessory olfactory systems in the development of maternal behavior in the primiparous Wistar rat. Females underwent one of the following treatments: vomeronasal nerve section (VN), irrigation of nasal cavities with 5% ZnSO4 solution (ZN), surgical control, saline irrigation control, and normal control. Surgical or first irrigation were done before mating occurred. Irrigations were done every 7 days thereafter. The dams and their litters were observed from the day the litter was born (Day 1) through Day 16. Pup weights and temperatures were recorded daily. Home cages were checked daily for changes in nest location and number of times pups were found out of the nest. Retrieving tests were conducted on Days 4, 7, 10, and 13. The following behavioral items were observed: number of pup retrievals , number of times mother nosed or licked pups, percentage of litter returned to nest by end of test, dam self-grooming, dam climbing or rising, and dam digging or burrowing in shavings. The VN dams and their litters were not significantly different from the control dams and their litters on any of the measures taken. The ZN dams and their litters were not significantly different from their controls on all measures except for pup body temperature which was slightly lower from Day 13 through day 16 and pup body weight which was slightly lower from Day 12 through Day 16. Since these differences are very small, they do not seem to indicate a serious deficiency in maternal behavior. The results indicate that adequate maternal behavior develops with either of the two systems intact.     

A word’s meaning affects the decision in lexical decision

The influence of an isolated word’s meaning on lexical decision reaction time (RT) was demonstrated through four experiments. Subjects in two experiments made lexical decision judgments, those in a third experiment pronounced the words used in the lexical decision task, and those in a fourth experiment quickly pronounced their first associative response to the words. Differences in lexical access time for the words were measured with the pronunciation task, and differences in meaning were assessed with the association task. Multiple regression analyses of lexical decision RT were conducted using associative RT, pronunciation RT, and other target word properties (printed frequency, length, instance dominance, and number of dictionary meanings) as predictor variables. These analyses revealed a relationship between lexical decision RT and associative RT after the effects of other variables had been partialed out. In addition, word frequency continued to have a significant relationship to lexical decision RT beyond that shared with pronunciation RT and the other variables. The results of these experiments indicate that at least some of the effect of word meaning and word frequency in lexical decision is attributable to a decision stage following lexical access.     

Lateral asymmetry of personal optimism

By combining models of cerebral emotional asymmetry and unilateral hemispheric activation, it was hypothesized that orienting to the right would produce greater personal optimism about future events than would orienting toward the left. This was supported significantly in two experiments which differed from each other in their manipulations, hypothetical future events, means of responding, and settings. The results supported previous research on unrealistic optimism and extended the concept to show the effect of induced lateral orientation. It was proposed that this effect is mediated by mood, and possibly by perceived control, and that this methodology can be extended to other behaviors which have proven amenable to mood manipulation.     

Stimulus selection in passive avoidance learning and retention: weanling, periadolescent, and young adult rats

Periadolescent rats exhibit a number of behavioral differences in comparison with younger or older animals. For instance, periadolescents tend to show enhanced acquisition of simple active avoidance tasks, but impaired acquisition of more complex appetitive and aversive discriminations. In this experiment, rats were trained on a simple passive avoidance task at one of three ages, as weanlings (25 days), periadolescents (35 days), or young adults (45 days). Training occurred in the presence of both a redundant discriminative stimulus and a specified, redundant contextual stimulus. The periadolescents did not differ from either younger or older rats in rate of learning the passive avoidance task. The retention performance of these animals was then tested following a change in either, neither, or both of the redundant cues. When a measure of performance that controls for baseline activity was used, it was observed that periadolescents were not disrupted by a change in the redundant discriminative stimulus, a cue change that clearly disrupted performance in 25- and 45-day-old animals, and tended to be more disrupted by the contextual change than younger or older rats. It is hypothesized that the alterations in performance exhibited by periadolescents may be related to an ontogenetic alteration in stimulus selection modulated by the catecholaminergic systems.