Stimulus Events Research Articles

Excitation and inhibition in unblocking.

In four experiments the nature of learning established with unblocking procedures in the appetitive conditioning of rats was examined. Measures of learning included response topography, effects of selective satiation, and summation and retardation tests of conditioned inhibition. One cue (A) was first paired with either a single unconditioned stimulus event, US1, or a sequence of two events, US1----US2. US2 was either qualitatively similar to (US2-Same) or different from (US2-Diff) US1. Then, a compound of A and a novel cue (X) was reinforced with US1 or US1----US2. Conditioning to X was blocked if either the single US1 or the US1----US2 sequence was used in both phases. If X accompanied an upshift in the reinforcer, from US1 to US1----US2, it acquired conditioned responding, especially when US2-Diff was used. Responding in the latter case was the consequence of both X-US1 and X-US2 associations. In Experiments 1-3, if X accompanied a downshift from US1----US2-Same to US1, it acquired conditioned responding that was based on X-US1 associations, but if it accompanied a downshift from US1----US2-Diff to US1, it acquired conditioned inhibition based on X-US2 associations. In Experiment 4, X acquired net inhibition at short US1-US2 intervals and net excitation at longer intervals, with downshifts from either US1----US2-Same or US1----US2-Diff to US1. However, the interval gradient was broader with downshifts from US1----US2-Diff. These data, and several other contradictory findings in the unblocking literature, are consistent with the views that (a) the surprising addition or deletion of US2 in unblocking experiments both facilitates the acquisition of excitatory X-US1 associations and establishes either excitatory or inhibitory, respectively, X-US2 associations, and (b) that the gradient of X-US1 facilitation is broader than that of X-US2 association.

Hypnotically induced pseudomemories--sampling their conditions among hypnotizable subjects.

Three studies are reported in a program of research that investigated a range of parameters affecting individual differences in the incidence of hypnotically induced pseudomemory among hypnotizable subjects. Study 1 replicated Laurence and Perry's (1983b) base rates for hypnotically induced pseudomemory response among hypnotizable subjects; in Study 2 the same response was analyzed under more strictly controlled stimulus conditions. Study 3 was an investigation of the impact of a broader range of stimulus events on response and a more sensitive test of the hypothesis that individual differences in pseudomemory effects are tied essentially to the social context of hypnosis. In all three studies, independent groups of subjects were tested who were highly responsive to hypnotic suggestion. Data indicated that the incidence of pseudomemory response was stable and consistent when stringent criteria of scoring were adopted. Also, for some subjects, real and suggested memories were maintained at one and the same time when hypnotically induced memory was examined in different test settings, suggesting that pseudomemories do not permanently overlay real experience. Overall, contextual factors appeared to play a major role among susceptible subjects in determining the nature and incidence of hypnotically induced pseudomemories.

Diurnal Variation, Task Characteristics, and Vigilance Performance

Three experiments consider the effects of several task features along with the time of day when vigilance was tested. The first experiment found that detections on the Bakan task depended on event rate and signal frequency and that the adverse effects of lowering signal frequency were more marked in the afternoon than in the morning. The second experiment found that the typical sensitivity decrement on a brief, rapidly paced successive discrimination task occurred earlier when the stimuli were degraded—especially in the early evening as compared with the morning—and that a riskier criterion placement was adopted in the evening. The third experiment used an unpaced simultaneous discrimination task with equiprobable stimulus events. Efficiency was not stable but declined as time passed, while speed increased. These changes tended to be more apparent in the afternoon, and perceptual efficiency seemed genuinely lower than in the morning. The implications for interpretations of vigilance and time-or-day effects are discussed.

Infants' intermodal perception of two levels of temporal structure in natural events

Infants' intermodal perception of two levels of temporal structure uniting the visual and acoustic stimulation from natural, complex events was investigated in four experiments. Films depicting a single object (single, large marble) and a compound object (group of smaller marbles) colliding against a surface in an erratic pattern were presented to infants between 3 and 7 1 2 months of age using an intermodal preference and search method. These stimulus events portrayed two levels of invariant temporal structure: (a) temporal synchrony united the sights and sounds of object impact, and (b) temporal microstructure, the internal temporal structure of each impact sound and motion, specified the composition of the object (single vs. compound). Experiment 1 demonstrated that by 6 months infants detected a relation between the audible and visible stimulation from these events when both levels of invariant temporal structure guided their intermodal exploration. Experiment 2 revealed that by 6 months infants detected the bimodal temporal microstructure specifying object composition. They looked predominantly to the film whose natural soundtrack was played even though the motions of objects in both films were synchronized with the soundtrack. Experiment 3 assessed infants' sensitivity to temporal synchrony relations. Two films depicting objects of the same composition were presented while the motions of only one of them was synchronized with the appropriate soundtrack. Both 4 1 2 - and 6-month-olds showed evidence of detecting temporal synchrony relations under some conditions. Experiment 4 examined how temporal synchrony and temporal microstructure interact in directing intermodal exploration. The natural soundtrack to one of the objects was played out-of-synchrony with the motions of both. In contrast with the results of Experiment 2, infants at 6 months showed no evidence of detecting a relationship between the film and its appropriate soundtrack. This suggests that the temporal asynchrony disrupted their detection of the temporal microstructure specifying object composition. Results of these studies support on invariant-detection view of the development of intermodal perception.

Ontogenesis of trace conditioning in young rats: dissociation of associative and memory processes.

Hooded rats from 15 to 30 days of age were trained with a Pavlovian trace fear conditioning procedure in order to study the development of their capacity to learn associations between events separated in time. For both the auditory and visual systems, the associative processes necessary to learn about temporally contiguous events emerged earlier during ontogenesis than the processes necessary to integrate events separated in time. Furthermore, the ability of the rats to integrate events separated by increasingly long intervals continued to improve as they got older. We suggest that the emergence of the capacity to integrate temporally separate events reflects the maturation of memory processes that retain representations of stimulus events over time, and that these processes continue to mature for a considerable period after the basic associative processes have become functional.

Spotlight failure in covert visual orienting

An important property of visual orienting is that the metaphorical “beam” is aimed at a location in space, and should therefore affect performance on any stimuli that occur at attended (producing benefits) or nonattended (producing costs) locations. Three experiments are reported that challenge this property. We used a precuing paradigm in which centrally presented arrows indicated the likely location of a probable stimulus event, which the subject had to discriminate from’ an improbable event. In each experiment the probable stimulus-response pairing showed significant cuing effects (costs + benefits), whereas the improbable stimulus-response pairing did not. This finding suggests that covert endogenous (centrally presented cues) orienting is not well characterized by the spotlight metaphor. Under these conditions, subjects seem to be generating a more specific expectancy.

Cued recall of specific memories in children and adults

The goal of this study was to determine some of the factors that contribute to developmental differences in using cues to retrieve specific memories. Second- and fifth-grade children and college adults were shown adjective noun-noun word stimulus events (e.g., bloody axe-sword), in which the adjectives strongly modified event meaning, and asked acquisition orienting questions that amplified (specific questions) or diluted (category questions) event specification. In addition, the stimuli were presented once only (one trial) or there was a repeated presentation with a constant or varied orienting question on the second presentation. At retrieval, orienting questions were asked of the retrieval cues that were the same as the acquisition questions, semantically related to the acquisition questions, or no questions were asked, and the retrieval cues reinstated the acquisition context (adjective noun cues) or represented the nominal type of event that was experienced (noun cues). The one-trial results showed that the children had less success than the adults using in the adjective noun retrieval cues for no questions and the related questions, relative to same questions, and also that the children used the noun cues particularly ineffectively. The event repetitions modified these patterns in predictable ways. The results suggest that type information may mediate the use of cues to retrieve specific memory tokens, and type information seems more salient in adult than in child event representations in memory.

Memory for associative history of a conditioned stimulus

The common assumption that the current, but not the past, associative status of a conditioned stimulus (CS) is represented in memory is examined with respect to various behavioral phenomena within the existing literature and is found to be inadequate. This assumption is frequently expressed as associative path independence, which posits that the memorial effects of stimulus events occurring during a conditioning trial depend only on the associative strength of the CS at the initiation of that trial. Twelve laboratory phenomena are reviewed in which behavior is readily interpretated in terms of subjects remembering past as well as present associations. The possibility that behavior is influenced by past associative states as well as current associative strength is contrasted with several alternative explanations, including the suggestion that the current associative state of a CS is defined by variables in addition to associative strength. However, these alternatives are only partially successful without additional assumptions that increase their complexity. Contrary to many prevailing models, we conclude that subjects appear to retain the associative history of a CS.

Perceived structure and the maintenance of attention

It was hypothesized that people can attain complex, hierarchically organized structures for incoming task-relevant information; that the boundaries between the units of information highest in the hierarchy constitute major breaks in the processing and integration of information; and that these major “breakpoints” are times when people are especially vulnerable to distraction. Subjects were trained to perceive formally defined structures in sequences of stimuli. After training, subjects performed a continuous prediction/classification task, using the same sequences of stimuli. Distractors were present during some stimulus events, occurring at each level of the unit hierarchy. Subjects’ response times increased as unit level increased and in the presence of distraction. However, the major hypothesis was not confirmed: The effect of distraction did not vary with unit level. An alternative to this hypothesis is discussed, as well as limitations of the present test.

Evaluation of the relation between Pavlovian occasion-setting and instrumental discriminative stimuli: A blocking analysis.

Experiments with rat subjects used a blocking design (A+, then AB+) to assess the relation between Pavlovian occasion-setting and instrumental discriminative stimuli. Prior conditioning of both associative and occasion-setting functions of A in a serial feature-positive procedure blocked acquisition of an instrumental discriminative function by a novel stimulus (B) trained in compound with A. However, neither prior conditioning of only an A-US (unconditioned stimulus) association nor prior conditioning of Stimulus A using a Pavlovian simultaneous feature-positive procedure, which does not endow A with an occasion-setting function, blocked acquisition of an instrumental discriminative function by B. Prior acquisition of an instrumental discriminative function by A blocked acquisition of a Pavlovian occasion-setting function by a novel stimulus (B) trained in compound with A, but did not block acquisition of an association between B and the US. These outcomes indicate that Pavlovian occasion-setting and instrumental discriminative properties of a stimulus are functionally equivalent and that both Pavlovian occasion-setting and instrumental discriminative properties of a stimulus are functionally independent of simple associative relations between that stimulus and other events.

Reactivity, arousal, and coping with stress

This research stems from a recent finding (Klonowicz, 1987) that reactivity, which is considered as a basic dimension of temperament (Strelau, 1983), controls both the level of anticipatory arousal and its emotional tone. High reactives responded to conditions of uncertainty with a high level of general arousal and negative affect as reflected by their lesser readiness to work and higher self-reported levels of anxiety and tension. ‘Uncertainty’, in this study, referred to the questions of ‘what will happen’ and ‘when’ which constitute major sources of stress (Folkman, Schaefer and Lazarus, 1979; Lazarus and Launier, 1978). The negatively biased anticipation may reflect at least two phenomena. It seems possible that high reactives expect the worst and believe an unknown event to be potentially harmful. This pessimistic attitude may be the result of previous experience or general beliefs, like a belief in one’s own helplessness. The negative expectancy may interfere with effective coping both directly, through avoidance or unwillingness to initiate activity, and indirectly, by stimulating disruptive, negative emotions. Meichenbaum and Turk (1980) concluded that inadequate performance is related to self-referent negative thoughts involving preoccupation with imagined personal deficiencies, exaggerations of potential difficulties, and expectations of inefficacy. Carver and Scheier (1981) claim that worries are likely to reduce performance because they focus attention on the self rather than the relevant task. Another possibility is that the anticipatory ‘work of worrying’ may actually be a cognitive rehearsal which can facilitate the coping with future events (Breznitz, 1971; Fenz, 1975; Janis, 1958). This alternative suggests that there can be an advantage in the negative expectancy (cf. Epstein, 1973) even though it is inaccurate and will be eventually discarded (Klonowicz, 1987), because it may reduce the actual impact of a stimulus event. The current study was undertaken to investigate the effect of anticipated emotions on performance and aftereffects of performance in high and low reactive persons. The contrast in the two suggested outcomes of anticipatory arousal, increased or reduced performance, indicates that the empirical findings are thus far equivocal. While some data show that people can learn to modulate and use their emotions to good advantage, other data suggest the contrary. The effect of initial expectancies, or anticipation, depends on a number of factors such as the nature of the stressor and its duration (Averill, 1973; Harsh and Abbott, 1979), prior experience with the stressor (Epstein, Rosenthal and Szpiler, 1978; Fenz, 1975), controllability of the stressor or availability of means for coping, the duration of preparation time (i.e. the time allowed for anticipatory activity; Averill, O’Brien and Dewitt, 1977; Badia et al., 1979; Breznitz, 1967; Miller, 1979) accuracy of expectancies (Breznitz, 1976); individual differences in coping strategies (Averill et al., 1977; Miller, 1979), and stress relevant information (Averill, 1973; Cohen and Lazarus, 1973; Janis, 1958). Moreover, the literature suggests that there is no simple relationship between any of these factors and subsequent functioning and that the various factors interact in affecting performance. As an example, the classical studies of Fenz (1975) and Epstein indicated that the timing of anticipatory arousal depended on the experience with the stressor. The complexity of the variables and their effects is the reason why no specific hypotheses were formulated for the current study which concerns the effects of anticipation on subsequent functioning of lowand highreactive persons. An additional problem investigated in this study concerns the positive aftereffects of work. The literature in this area (Cohen, 1980; Klonowicz, 1973, 1974, 1985) suggests a great preoccupation

Retrieval search for category and thematic information in memory by children and adults

Retrieval search for the last target word of four noun category (Bus-Airplane-Car-Train) and thematic (Suitcase-Coat-Ticket-Train) stimuli by children and adults was examined in four experiments. Stimulus classification at acquisition was ensured by orienting questions. Associative search structures were externalized more or less at retrieval by providing cues reinstating the whole (Bus-Airplane-Car) or only part (Bus-Airplane, or Bus) of the associative context, cues with the same or changed (Car-Bus-Airplane) word order, or cues representing the stimulus classification (Vehicle). The results suggest that the associative structures of memory help constrain and mediate retrieval search for stimulus information, and that these structures as well as representations of the stimulus events in memory seem to differ for thematic and category events, and for children and adults, contributing to search differences.

Consistent and varied training in the theory of automatic and controlled information processing

In their theory of automatic and controlled information processing, Schneider and Shiffrin (1977; Shiffrin & Schneider, 1977) assign a central role to the distinction between consistent and varied stimulus-response mapping. The present note shows that this distinction cannot be made without specification of what is to count as a unit in describing stimulus events. In any rule-governed task, including what Schneider and Shiffrin call varied-mapping search, there is a description of stimulus events which is consistently mapped on to responses. It follows that their results are concerned not with the importance of consistency per se, but with a specification of the important level of stimulus description for one particular task (visual search). Their results show directly that not all forms of consistent mapping lead to automatic processing. Attempts to generalize their work should be concerned with the issues of which forms of consistency are effective.

Chance Expectancy with Trial-By-Trial Feedback and Random Sampling Without Replacement

Most of the easily accessible statistical models for estimating chance performance assume random sampling with replacement, but the objectives of psychological experiments commonly require sampling without replacement. It is often desirable, for example, to administer a repeated series of measurements to the same individual while balancing conditions, types of stimulus event, or types of response alternative. Since both human and nonhuman subjects can detect the nonrandom effects of sampling without replacement (Jenkins, 1965), a precise estimate of chance performance must take this into account. Consider the following experimental example generated by a well-known and hotly-disputed theoretical question. Gardner and Gardner (1978) reared five chimpanzees, Washoe, Moja, Pili, Tatu, and Dar, under conditions that closely simulated the rearing conditions of human infants. Where earlier experiments in cross-fostering such as Kellogg and Kellogg (1933) and Hayes and Hayes (1951) used speech, Gardner and Gardner used American Sign Language (ASL), the gestural language of the deaf in North America. Naturalistic observations of the young chimpanzees yielded results that closely approximate the results of similar observations of very young human children. While other developmental similarities were accepted without dispute, the evidence for verbal skills generated heated controversy (e.g., Umiker-Sebeok & Sebeok, 1980). One of the more pertinent arguments that have been raised concerns the validity of adventitious, naturalistic observations, particularly in the case of verbal behavior. Under the rich, informal conditions of cross-fostering, observers may read more meaning than is actually present in the signs. The fact that the remarkable linguistic skills that have been attributed to very young human children are based on equally informal observations (c.f. Bloom, 1970; Brown, 1973) only serves to underscore the need for more stringent evidence. Early in Project Washoe, Gardner and Gardner (1971, pp. 158-161) began a series of vocabulary tests designed to demonstrate that cross-fostered chimpanzees could communicate to a human observer under conditions in which the only information available to the observer was the sign language of the chimpanzees. To accomplish this, exemplars of nameable objects were photographed on 35-mm slides which were back-projected on a screen that could be seen by the chimpanzee subject, but could not be seen by the observers. A second objective was to demonstrate that independent observers agreed with each other. To accomplish this, there were two observers. The first observer served as interlocutor in the testing room with the chimpanzee.

Alcohol and vigilance performance: effect of small doses of alcohol on simple visual reaction time.

The effects of small doses of alcohol were tested in a vigilance setting. Subjects were repeatedly tested during three 30-min. sessions. The stimulus event was a visual light located in front of subjects. The average intersignal interval was 3.75 sec., and the dependent measure was simple reaction time. Analysis indicates that alcohol produced a skewness in the RT-distribution with time on task; the longer reactions increased more than the shorter ones. Especially the extremely long reactions (blockings) increased markedly with time on task under alcohol. Results were discussed in relation to other studies reporting divergent results in similar test situations.

Constraints imposed on taste physiology by human taste reaction time data

The speed with which an organism responds to stimulus events is reaction time (RT): the minimum time interval between stimulus arrival at a receptor organ, and an overt response by the organism. This time interval specifies maximum duration of all processes necessary for the RT sequence. Responses to any change in taste have RT less than 1 sec for suprathreshold concentrations. Therefore, constituent events at taste receptors, in the central nervous system (CNS), and at the response organ, must have sufficient durations less than 1 sec (Constraint 1). Taste stimulus durations of 50 msec, and therefore taste receptor events of approximately 50 msec, are sufficient for these responses (Constraint 2), as well as for taste quality identification responses (Constraint 3). Taste receptor latencies, neural conduction times, and RT response organ events are even briefer. Thus, 60% to 90% of human taste RT is CNS events. Taste receptor events remain crutial, but CNS processing is important, and apparently time limiting, in all human taste judgments.

Norm theory: Comparing reality to its alternatives.

A theory of norms and normality is presented and applied to some phenomena of emotional responses, social judgment, and conversations about causes. Norms are assumed to be constructed ad hoc by recruiting specific representations. Category norms are derived by recruiting exemplars. Specific objects or events generate their own norms by retrieval of similar experiences stored in memory or by construction of counterfactual alternatives. The normality of a stimulus is evaluated by comparing it to the norms that it evokes after the fact, rather than to precomputed expectations. Norm theory is applied in analyses of the enhanced emotional response to events that have abnormal causes, of the generation of predictions and inferences from observations of behavior, and of the role of norms in causal questions and answers. This article is concerned with category norms that represent knowledge of concepts and with stimulus norms that govern comparative judgments and designate experiences as surprising. In the tradition of adaptation level theory (Appley, 1971; Helson, 1964), the concept of norm is applied to events that range in complexity from single visual displays to social interactions. We first propose a model of an activation process that produces norms, then explore the role of norms in social cognition. The central idea of the present treatment is that norms are computed after the event rather than in advance. We sketch a supplement to the generally accepted idea that events in the stream of experience are interpreted and evaluated by consulting precomputed schemas and frames of reference. The view developed here is that each stimulus selectively recruits its own alternatives (Garner, 1962, 1970) and is interpreted in a rich context of remembered and constructed representations of what it could have been, might have been, or should have been. Thus, each event brings its own frame of reference into being. We also explore the idea that knowledge of categories (e.g., encounters with Jim) can be derived on-line by selectively evoking stored representations of discrete episodes and exemplars. The present model assumes that a number of representations can be recruited in parallel, by either a stimulus event or an

Helping parents of premature babies: A cognitive-behavioral approach

Having an infant in an intensive care setting is highly stressful for parents and may disrupt the bonding process. This article presents a cognitive-behavioral framework as a useful way of understanding and intervening with parents of normal, healthy, premature babies. Differences are shown between stimulus events experienced by parents of term and premature babies and the consequent differences in thoughts, feelings, and behaviors are discussed. Suggestions are made for helping parents of premature babies replace dysfunctional irrational cognitions with more appropriate and rational beliefs.

An integrated approach to computer usage in the teaching of experimental psychology

Ongoing development of a series of laboratory modules for experimental psychology courses is described. The modules are designed to be implemented on a network of TRS-80 microcomputers, which are linked by a Network 3 controller. Within each module, the computer controls stimulus events, records individual data, probes the student for understanding of experimental concepts, and tabulates the class data. In addition to a discussion of the modules and their software implementation, the required hardware is described.

Scale effects in memory for the time of events.

This study addressed the question of how people remember the time of past events. Stimuli were 10 news events that had occurred from 6 months to 20 years before the study. In contrast to previous studies of memory for time, subjects were asked to provide estimates of the stimulus events on multiple time scales, including year, month, day of the month, day of the week, and hour. If judgments are based on direct information about the age of the memory, accuracy should decrease monotonically as one moves to finer scales. Alternatively, if subjects reconstruct the time from fragmentary information associated with the event, one would expect that estimates on finer time scales would often exceed grosser scales in accuracy. Results for accuracy, confidence, and number of recall cues supported the latter position. In addition, subjects reported a variety of types of recall cues, the most common being memory for personal experiences or events that were contiguous with the news event.