Effect of prior Pavlovian discrimination training upon learning an operant discrimination

The effect of Pavlovian discrimination training with two stimuli upon subsequent learning of an operant discrimination involving those stimuli was studied. After preliminary lever press training, the lever was removed and thirsty rats received noncontingent pairings between S₁ (a tone or a clicker) and water reinforcements, whereas S₂ (a clicker or a tone) occurred always without reinforcement. This procedure presumably established S₁ as a positive CS for respondent behavior, whereas S₂ was established as an inhibitory CS. Following this training, the lever was reintroduced and the rats were trained on an operant (lever pressing) discrimination involving S₁ and S₂. For the Consistent Ss, S₁ was the S^D and S₂ the S^Δ in the operant discrimination; for the Reversed Ss, S₂ served as S^D and S₁ as S^Δ. The Consistent Ss learned the operant discrimination significantly faster than did the Reversed Ss. The result emphasizes the importance of respondents, conditioned to S^D and S^Δ, which modulate operant performance to these stimuli.     

Errorless establishment of visual discrimination using fading procedures

A visual discrimination task involved presenting a triangle briefly as a sample. When it was withdrawn, this triangle and two others differing slightly in degree of rotation were presented in different positions, with S required to locate the sample that had been presented. Discrimination proved difficult for preschool children. When only the correct triangle was illuminated, discrimination was readily established. The brightness difference between correct and incorrect matches was gradually faded out by increasing the intensity of the incorrect matches, until they were equal in brightness to the correct match. The discrimination established by brightness difference was maintained in its absence, thereby transferring stimulus control from brightness to form, in an almost errorless sequence.     

Elevation easier than plan for sighted and early-blind adults in a perspective-taking task

Plans show shapes of objects from above, and represent both their left–right order and their order in the z-dimension (the distance of the objects). Elevations show only the vertical shapes of objects arranged from left to right. Plans, having more spatial information, may be more difficult for participants to construct. Results from a study with sighted, sighted-blindfolded, and early-blind participants on Piaget's perspective-taking three-mountain task support this hypothesis. The plan task was judged more difficult than the elevation task even when participants performed with the same level of accuracy on both tasks. In visual and tactile tasks, amount of spatial-order information may determine difficulty, rather than plan versus elevation per se.     

Stimulus interaction and transfer of discrimination in children

Two discrimination learning experiments on third- and fourth-grade children are reported. In Expt I, Ss received either simultaneous or successive pretraining followed by simultaneous or successive transfer tasks in which an irrelevant dimension was varied either between or within settings. With the incorporation of a response-produced cues proposal, a modified version of the Hull-Spence theory (C. C. Spiker, Psychological Review, 1970, 77, 496–515) accounted for 81.2% of the variance of the group means and provided a satisfactory method of both quantifying and manipulating the mechanisms of associative transfer, even when the dimensions of pretraining and transfer differed. Because simultaneously pretrained Ss performed more as was expected than did successively pretrained Ss, it was hypothesized that Ss have an extraexperimental tendency to respond to dimensions varying within settings. This hypothesis was supported by the results of Expt II, in which an extensive shaping procedure was used for simultaneous, successive or control pretraining tasks followed by a successive transfer task in which the arrangement of two irrelevant dimensions was manipulated.     

Slow potential changes and choice reaction time as a function of interstimulus interval

Slow potential changes were recorded over the vertex (C_z) during a choice reaction task. The constant interstimulus interval (ISI) between the visual warning (S₁) and the visual imperative signal (S₂) was either 200, 400, 1000 or 2000 msec. The contingent negative variation (CNV) was not only measured between S₁ and S₂ (CNV₂), but also before S₁ (CNV₁).The main results were: (1) The CNV₂ amplitude showed significant variation as a function of ISI. It reached its maximum with an ISI of 1000 msec. (2) CNV₁ developed only before the short ISIs (200 and 400 msec). (3) When CNV₁ and CNV₂ were summed the differences in CNV amplitudes and durations between different ISIs became smaller. (4) The peak-to-peak amplitude P₁-N₁ of the potential evoked by S₁ was enhanced with short ISIs. (5) The correlations between mean CNV and median reaction time (RT) were low but significant for ISIs of 400, 1000 and 2000 msec. When, however, the effect of subjects was partialized out these correlations were drastically reduced, whereas the partialization of session and block effects had no noticeable influence on these correlations. (6) The correlations between single RT and single CNV (measured for the ISI of 1000 msec, individually for two subjects) were weak or even completely lacking.The main conclusion was that CNV coincides with preparedness to react to a stimulus in a choice RT-task, but its amplitude at the moment of onset of the imperative stimulus does not reflect, or reflects weakly, the degree of preparedness (as indicated by RTs) at that moment.     

An assessment of response bias for thesame-different task: Implications for the single-interval task

Two auditory amplitude discrimination experiments were conducted using thesame-different experimental design. Observer bias was manipulated, in the first experiment, by varying payoff matrices and, in the second, by varying prior probabilities of signal presentation. Five levels of bias manipulation and four levels of difficulty were employed in each experiment. Each observer received all combinations of bias manipulation and difficulty, but with only one of these combinations within each block of trials. Nine indices of bias were assessed by simultaneously fitting isosensitivity and isobias functions to the data and by fitting isobias functions only. Although none of the indices tested provided an exceptionally good fit to the data, two indices stood out from the rest. These werec _sd ^* andc _i, indices with isobias contours similar in shape to those for thec index derived from theyes-no task.     

The requirements of truth and of justification of premisses

Summary The article attempts to give an answer to the question: why for the acceptance of a statementz ₂ implied by another,z ₁, it is required not only thatz ₁ be true but also justified? The application in a given case of the rule allowing to accept a statement implied by another true one is not possible without establishing in an appropriate manner that the statement is true. Practically, therefore, we have to rely in the conditions for the acceptance of a statementz ₂ implied by anotherz ₁ on the manner of acceptance ofz ₁. If we require that this manner of acceptance should guarantee the truth ofz ₁, no special requirement of the truth ofz ₁ is necessary. If the acceptance ofz ₂ implied byz ₁ depends onz ₁ being accepted in a manner which does not ensure the truth ofz ₁ (e. g. by induction), then we have to give up the requirement of the truth ofz ₁. At most, we may prohibit the acceptance ofz ₂ implied byz ₁, inductively justified, if the evidence for the negation ofz ₁ is better than the inductive one forz ₁.     

The role of overt activity in children's sentence production

Nursery schooler's abilityto associate pairs of toys was assessed under four experimental conditions: (1) control, (2) S manipulating the toys, (3) S generating a sentence, and (4) S generating a sentence while manipulating the toys. All three S-involvement conditions produced significantly better recognition performance than the control but contrary to initial predictions, the difference between the sentence-only and sentence-plus-manipulation conditions was not significant. In contrast to previous research, Ss in the sentence-only conditions had little difficulty producing sentences when asked. Of interest was the finding that the quality of sentence production was poorer in the sentence-plus-manipulation condition than in the sentence-only condition. Results are discussed in terms of the possible “conflict” produced when the child is required to engage in more than one overt activity simultaneously.     

Multilinear representations for ordinal utility functions

An ordinal utility function u over two attributes X₁, X₂ is additive if there exists a strictly monotonic function ϕ such that ϕ(u) = v₁(x₂) + v₂(x₂) for some functions v₁, v₂. Here we consider the class of ordinal utility functions over n attributes for which each pair of attributes is additive, but not necessarily separable, for any fixed levels of the remaining attributes. We show that while this class is more general than those that are ordinally additive, the assessment task is of the same order of difficulty, and involves a hierarchy of multilinear rather than additive decompositions.     

Perceptual learning in pigeons: Decreased ability to Discriminate samples mapped onto the same comparison in many-to-one matching

Humans often treat two stimuli that are associated with a common response as similar in other contexts. They do so presumably because those stimuli become conceptually or perceptually more similar to each other (perceptual learning). An analogous phenomenon may occur in pigeons when they are trained with a matching-to-sample procedure in which more than one sample is mapped onto the same comparison. In the present research, pigeons were trained to select one comparison following either of two samples (S₁ or S₂) and to select the other comparison following either of two different samples (S₃ or S₄). When the samples were then presented as positive and negative stimuli in a simple successive discrimination, samples that had been associated with the same comparison during original training (e.g., S₁ vs. S₂) were more difficult to discriminate than were samples that had been associated with different comparisons (e.g., S₁ vs. S₃). Thus, it appears that perceptual learning occurs in pigeons as well.     

The nature of equity-restoration: Some approval-seeking considerations

Subjects performed a proofreading task and evaluated its difficulty both beforehand and afterwards. They were overpaid or equitably paid by an experimenter who was or was not directly responsible for the level of pay they received, and who they believed would or would not see their post-test ratings. All subjects knew the experimenter would grade their task performance. Consistent with equity theory, overpaid subjects rated the task as having been more difficult than they had expected and did higher quality work than did equitably paid subjects. However, subjects who thought the experimenter would see their ratings (Aware condition) rated it as more difficult and performed more poorly on it than those who thought she would not see them (Unaware condition). Reported task difficulty increased among overpaid subjects under aware conditions, remained stable among overpaid subjects under unaware conditions, and decreased for equitably paid subjects. These findings suggested that what appears to be “equity-restoration” may be a self-presentation strategy designed to win the experimenter's approval, and that task ratings rather than performance will be used for this purpose when they can be communicated to the experimenter. The experimenter's responsibility for the subject's pay had no effect in the present study.     

The Relationship between Performance in Near Match-to-Sample Tasks and Fluid Intelligence

Match-to-sample is a timed task in which a subject is presented with a visual stimulus (the probe) and must select a match to that stimulus (the target) from among an array of distractors. These tasks are frequently employed as tests of basic cognitive abilities and demonstrate consistent correlations with measures of intelligence. In the current study, a match-to-sample task was modified to produce near-match conditions (trials for which no exact match existed). Two factors were manipulated: type of discrepancy between the target and probe (additive or subtractive) and degree of discrepancy between target and probe (1 element or 2 elements). It was hypothesized that introducing near-match conditions would change the processing demands of the task, resulting in increased correlations between decision time and fluid intelligence. Degree and type of discrepancy affected decision times: participants required more time for 2 element discrepancies and additive type discrepancies. Contrary to expectations, increased decision time on a task did not correspond to higher correlations with fluid intelligence. For type, correlations were larger when participants needed to mentally subtract elements from the target in order to make it match the probe (mean r_additive = .399; mean r_subtractive = .451). For degree, correlations were larger for trials where the probe and target differed by one element (mean r = .470) than for trials where the probe and target differed by two elements (mean r = .380). These results seem to indicate that the relationship between the complexity of a task and general intelligence is not as straightforward as has been commonly believed.     

Interaction of reinforcement conditions and developmental level in a two-choice discrimination task with children

A total of 540 first, fourth, and eighth graders, equally divided by sex, were run on a two-choice discrimination task under one of three reinforcement conditions: reward (R) for correct responses, punishment (P) for incorrect responses, or reward and punishment (RP) for correct and incorrect responses. Half the Ss were tested by a male E; half, by a female E. Across all developmental levels, learning was superior in the P group. Complex interactions involving sex of S and E underline the importance of organismic variables in discrimination learning and in specifying parameters of reinforcer effectiveness.     

Personality and performance on a missing-letter measure of perceptual defence

Fifty-two Ss were required to make complete words from 20 neutral and 20 unpleasant ‘target’ words whose alternate letters had been removed. The four personality scales from the EPQ and the Psychoticism scale from the unpublished PEN inventory were employed as independent variables in repeated-measures analyses of variance in which the dependent variable was the number of neutral or bad target words produced in the missing-letter task. A significant two-way interaction was obtained between PEN Psychoticism and performance on the task, such that Ss scoring low on the personality scale hit significantly more neutral targets than Ss scoring high on the scale. These results did not support previous studies on the relationship between personality and perceptual defence and were interpreted within the framework provided by Mednick, whereby schizophrenia is characterized by a flattening of associative hierarchies.     

The effects of control and lack of control on active and passive avoidance in rhesus monkeys

Most studies which have examined the effects of lack of control have utilized test tasks in which active responding is required, and generally they have found impaired learning. Those few studies which have required passive responding in the test task generally have found facilitation of learning. The present two experiments examined the effects of lack of control in both active and passive avoidance tasks in a primate species (Macaco mulatta) not previously used in this research area. In Experiment 1, although the group without control (IE) tended to be inferior at active and superior at passive avoidance in comparison to the group with control (E), there were no significant differences. In Experiment 2, utilizing a difficult discrimination task in which subjects were required to learn when and when not to respond actively to avoid aversive stimulation, greater group differences were found. Two monkeys from Group IE failed to escape in active avoidance acquisition and, as a whole. Group IE was somewhat slower to respond than Group E. At passive avoidance, however. Group IE was superior to Group E and, as a consequence, more efficiently solved the discrimination problem. Implications of the present results for interpretation of the effects of lack of control as deficits are discussed.     

“Generalized imitation” on a nonimitative task: Effects of modeling and task history

Two experiments investigated characteristic generalized imitation procedures on a nonimitative successive visual discrimination task. In Experiment I, no discriminative behavior was obtained though a number of procedures designed to enhance discrimination were employed. The introduction of a differential modeling procedure after nine or 10 sessions of nondifferential performance was ineffective in producing differential responding for three of four Ss. In the second experiment, the differential modeling procedure was introduced as an initial manipulation and was successful in establishing discriminative performance in all Ss. After several sessions of differential responding, the observation of a model performing nondifferentially was relatively ineffective in altering the pattern of responding. These results suggest (1) that modeling may be functional in altering a S's behavior depending on what point in the procedures the manipulation is introduced and (2) that certain procedural variables may define a functional response class characterized by the failure to develop discriminative responding.     

A discrete time model for detection of randomly presented stimuli

Considered in this paper is a discrete-time Markov decision process with unobservable states, which occurs in equipment checking, medical diagnosis, signal detection, and reaction time studies. The process is characterized by (i) a state S₀ that at some unknown time t, which is determined probabilistically, turns into an absorbing state S₁; (ii) observations that provide fallible information about the true state and which are taken sequentially to determine whether or not the change from S₀ to S₁ has occurred; and (iii) losses for a false alarm and for delays in detecting the change. A response model is proposed, prescribing a terminal decision as soon as the posterior probability that S₁ obtains reaches or exceeds a fixed probability boundary. Predictions are derived concerning the probability of false alarm and several conditional distributions of the number of observations taken.     

Evidence for Age-related Changes to Temporal Attention and Memory from the Choice Time Production Task

ABSTRACT

The effect of aging on interval timing was examined using a choice time production task, which required participants to choose a key response based on the location of the stimulus, but to delay responding until after a learned time interval. Experiment 1 varied attentional demands of the response choice portion of the task by varying difficulty of stimulus–response mapping. Choice difficulty affected temporal accuracy equally in both age groups, but older participants' response latencies were more variable under more difficult response choice conditions. Experiment 2 tested the contribution of long-term memory to differences in choice time production between age groups over 3 days of testing. Direction of errors in time production between the two age groups diverged over the 3 sessions, but variability did not differ. Results from each experiment separately show age-related changes to attention and memory in temporal processing using different measures and manipulations in the same task.     

Influence of motivation and task difficulty on gender discrimination judgements

A study is reported examining how motivation to detect salary discrimination influences its detection depending on the difficulty of the detection task. Subjects were presented with information about the qualifications and salaries of female and male managers in 10 departments of a hypothetical company. This information was created so that female managers were undercompensated relative to their qualifications. The main dependent variable was subjects' ratings of gender discrimination. Independent variables were motivation and task difficulty. Based on Hull's drive theory an interaction effect was predicted and found: when the judgement task was easy, more gender discrimination was detected when motivation to detect discrimination was high rather than low, whereas when the judgement task was difficult, more gender discrimination was detected when motivation to detect discrimination was low rather than high. © 1998 John Wiley & Sons, Ltd.     

Decision and Response in Dual-Task Interference

Experiments with two stimuli (S₁and S₂) and two responses suggest the existence of a stage of processing that cannot be shared between two concurrent tasks. Widespread support has been found for the hypothesis that response selection for Task₂is postponed when the S₁to S₂stimulus onset asynchrony (SOA) is short (Pashler, 1994a). At short SOAs, manipulations which impact Task₂processing prior to response selection (e.g., degradation of stimulus quality) have little effect on Task₂response times (RTs). On the other hand, manipulations which are thought to impact response selection or execution (e.g., Stroop interference) always impact Task₂RTs. There is, however, one particularly compelling demonstration that appears to be inconsistent with the response selection bottleneck hypothesis: Karlin and Kestenbaum (1968) report that the RT difference between detection (i.e., 1-choice) and 2-choice discrimination dramatically decreases with decreasing SOA. Given that the primary difference between detection and discrimination is believed to be at response selection, their result may indicate a processing bottleneck at response execution (Keele, 1973). We fail to replicate the Karlin and Kestenbaum result in two substantive replications of Karlin and Kestenbaum's tasks and procedures. In the single experiment in which Karlin and Kestenbaum's result is replicated, a simple response execution bottleneck account is ruled out by the stability of the difference between 2-choice and 3-choice discrimination times across SOA. Two additional experiments demonstrate that response preparation and task strategy do not substantially contribute to the attenuation of response selection-level effects with decreasing SOA.