Primacy effects in self-attribution of ability1

Primacy effects in self-attribution of ability were investigated in an experiment. Subjects' performance on a 30-item test was experimentally manipulated to reflect one of three patterns: ascending, descending, or random success. It was predicted that there would be a primacy effect in self-attribution of ability regarding the task when subjects had no previous expectation or anchor to which performance could be assimilated, but that the primacy effect would be attenuated when a previous anchor existed. The presence or absence of a prior anchor was manipulated by describing the task as either a test related to intelligence or a test of an unsual ability, unrelated to previous experience. Results supported the hypothesis that there is a primacy effect in self-attribution of ability, and that this effect occurs most strongly where an individual has no prior anchor or expectation regarding his ability.     

Primacy and recency effects in nonhuman primates.

The reports of primacy and recency memory effects in nonhuman primates have been criticized because they have all used an initiating response. That is, the presentation of the to-be-remembered list of items was always contingent on a response being initiated by the nonhuman primate. It has been argued that this initiating response improves performance for early items in the list, resulting in the occurrence of the primacy effect, independent of any memory processing mechanism. This criticism was addressed in the present study by not using an initiating response prior to the presentation of the list. Nevertheless, both a primacy and a recency effect were observed in all 6 rhesus monkeys evaluated using a serial probe recognition task. Thus, the results are similar to those for humans, in that both primacy and recency effects can be obtained in nonhuman primates. A brief literature review is included, and it is proposed that the primacy and recency effects observed in humans, nonhuman primates, and infraprimates can be explained within the context of the configural-association theory.     

Primacy or recency effects in forming inductive categories

Five experiments provide evidence for a primacy effect in the formation of inductive categories. Participants completed a category induction task in which they observed and reproduced a set of lines that varied in length but were serially ordered so that they increased or decreased in length. Subsequent estimates of the average of the distribution were systematically biased in the direction of stimuli encountered at the beginning of the induction task, suggesting that initially encountered stimuli exert greater weight in a category representation than do subsequent stimuli. We offer possible explanations for why this primacy effect might arise.     

Intertrial effects of same-different judgements

Specific intertrial effects (repetition effects) and general intertrial effects (refractoriness or persisting attention to the preceding trial) were studied with the same-different judgment task, which dissociates the effects of response repetition and stimulus repetition. Response repetition alone did not facilitate performance. Stimulus repetition did aid performance, but mainly when accompanied by response repetition. Subjects tended to avoid the normal comparison process by using the (invalid!) “bypass rule” (Fletcher and Rabbitt, 1978): repeat the response if the stimulus or some aspect thereof (letter contents, size, position) is repeated from the preceding trial, otherwise change the response. As to general effects, partial refractoriness was evident at response execution, but not at earlier processing stages. Mean RT increased, but errors decreased, as the response-stimulus interval (RSI) between trials decreased. Presenting a new letter pair immediately after the preceding response produced a delay, but subjects used the waiting time, while the response system recovered or was redirected to the present trial, to improve the accuracy of their decision.     

Higher order sequential effects in psychophysical judgments

We found that the depth of sequential effects depends on the judgment task. An experiment with squares indicated that stimulus-response pairs up to two trials back were included in the judgment process when subjects were required to make category judgments of size, whereas only the immediately preceding event was incorporated when subjects were making magnitude estimations. In the case of category judgment, interactions between the current stimulus and prior stimuli as well as configural effects indicated that events one and two trials back meet an equivalent function in the judgment process and that these events may jointly operate in one trial. These findings can be explained by a class of models that assume that the position of preceding stimuli relative to the current stimulus is decisive in the judgment process. The multiple-standards model is a representative of this class according to which there are two types of standards: (1) the endpoints of the range as long-term standards and (2) traces of preceding stimuli as short-term standards.     

The effects of feedback in psychophysical tasks

Previous results of the reinforcement effects of feedback in psychophysical tasks have been interpreted as changes in the S’s response bias in the uncertain sensory state. The present study varied the percentage of feedback in a two-altemative loud-soft recognition task. The values of the probability of correct feedback were 1, .8, .6, .4, .2, and 0. The results indicated that Ss learned to respond to agree with the experimental feedback rather than with the actual cue presented on a trial. The probability of a response on Trial n +1 was highly dependent upon the response and feedback of Trial n only when the two trials were the same. It was concluded that feedback must influence the response probability vector associated with a given detection state.     

Higher order sequential effects in psychophysical judgments

We found that the depth of sequential effects depends on the judgment task. An experiment with squares indicated that stimulus-response pairs up to two trials back were included in the judgment process when subjects were required to make category judgments of size, whereas only the immediately preceding event was incorporated when subjects were making magnitude estimations. In the case of category judgment, interactions between the current stimulus and prior stimuli as well as configural effects indicated that events one and two trials back meet an equivalent function in the judgment process and that these events may jointly operate in one trial. These findings can be explained by a class of models that assume that the position of preceding stimuli relative to the current stimulus is decisive in the judgment process. The multiple-standards model is a representative of this class according to which there are two types of standards: (1) the endpoints of the range as long-term standards and (2) traces of preceding stimuli as short-term standards.     

The effects of conformity on recognition judgements

Schneider and Watkins (1996) demonstrated that participants' recognition performance can be affected by responses generated by a confederate. However, it remains uncertain whether the confederate's responses actually change the participants' memories or whether participants simply attempt to conform to the confederate. The present experiments examined this issue by having participants complete a final individual recognition test following a recognition test in which the participants worked with a virtual confederate. The results suggest that responses from virtual confederates affect participants' performance in ways similar to actual confederates and that conforming to a virtual confederate's responses does appear to result in actual deficits in memory. More specifically, it impairs participants' ability to correctly recognise material presented earlier.     

Primacy and frequency effects in absolute judgments of visual velocity

In absolute judgment tasks, identical stimuli are rated higher (or lower) when presented in a series of more frequent small (or large) stimuli. Using visual stimuli differing in velocity, we show that this conventional frequency effect is largely modulated by the primacy effect--that is, by the stimuli occurring on the early trials of a run. In Experiment 1, a frequency-like primacy effect was obtained with equal-frequent velocities. Identical velocities were rated faster when mainly slow rather than fast ones occurred on initial trials. In Experiment 2, we contrasted the frequency effect and the primacy effect: In runs with frequent slow velocities, mainly fast ones occurred earlier, whereas in runs with infrequent slow velocities, mainly slow ones did so. Lack of differences of ratings in the two conditions suggests that the two effects canceled each other. In Experiment 3, when mainly frequent velocities occurred earlier, the conventional frequency effect was obtained. We conclude that the conventional frequency effect represents a combination of the primacy effect and the pure frequency effect.     

Using contextual effects to derive psychophysical scales

This paper presents a functional measurement analysis of Parducci’s range-frequency theory. The theory provides a basis for (1)finding context-invariant psychophysical scales, (2)establishing the validity of rating scales, and (3) explaining contextual effects in judgment. In an experimental illustration, Ss judged the magnitude of numerals in nine different distributions. All data were used to obtain the psychophysical function for numerals and also to test the model. The large contextual effects were consistent with the model. Quantitative tests of fit supported the equal-interval assumption of the category scale. The psychophysical function appeared nearly linear but with a significant negative acceleration. The data were shown to be qualitatively inconsistent with generalizations of Helson’s theory of adaptation level and Johnson’s correlation-regression theory. They supported Parducci’s range-frequency theory and illustrated how it could be used to factor out contextual effects from effects of stimulus magnitude. Extensions of the range-frequency approach are also discussed.     

Contrast effects in typicality judgements: A hierarchical Bayesian approach

We examine the influence of contrast categories on the internal graded membership structure of everyday concepts using computational models proposed in the artificial category learning tradition. In particular, the generalized context model (Nosofsky, 1986), which assumes that only members of a given category contribute to the typicality of a category member, is contrasted to the similarity-dissimilarity generalized context model (SD-GCM; Stewart & Brown, 2005), which assumes that members of other categories are also influential in determining typicality. The models are compared in a hierarchical Bayesian framework in their account of the typicality gradient of five animal categories and six artefact categories. For each target category, we consider all possible relevant contrast categories. Three separate issue are examined: (a) whether contrast effects can be found, (b) which categories are responsible for these effects, and (c) whether more than one category influences the typicality. Results indicate that the internal category structure is codetermined by dissimilarity towards potential contrast categories. In most cases, only a single contrast category contributed to the typicality. The present findings suggest that contrast effects might be more widespread than has previously been assumed. Further, they stress the importance of characteristics particular of everyday concepts, which require careful consideration when applying computational models of representation of the artificial category learning tradition to everyday concepts.     

Contrast effects in typicality judgements: A hierarchical Bayesian approach

We examine the influence of contrast categories on the internal graded membership structure of everyday concepts using computational models proposed in the artificial category learning tradition. In particular, the generalized context model (Nosofsky, 1986), which assumes that only members of a given category contribute to the typicality of a category member, is contrasted to the similarity–dissimilarity generalized context model (SD-GCM; Stewart & Brown, 2005), which assumes that members of other categories are also influential in determining typicality. The models are compared in a hierarchical Bayesian framework in their account of the typicality gradient of five animal categories and six artefact categories. For each target category, we consider all possible relevant contrast categories. Three separate issue are examined: (a) whether contrast effects can be found, (b) which categories are responsible for these effects, and (c) whether more than one category influences the typicality. Results indicate that the internal category structure is codetermined by dissimilarity towards potential contrast categories. In most cases, only a single contrast category contributed to the typicality. The present findings suggest that contrast effects might be more widespread than has previously been assumed. Further, they stress the importance of characteristics particular of everyday concepts, which require careful consideration when applying computational models of representation of the artificial category learning tradition to everyday concepts.     

Serial position curves in spatial memory of rats: Primacy and recency effects

Memory for lists of items was tested in rats (N = 18) in an 8-arm radial maze. In Experiment 1 trials consisted of a study phase, in which the rat could freely choose five arms to obtain a food reward, and a test phase in which the animal was presented with a choice between a novel and a previously visited arm. The rat received additional food reinforcement only when visiting the novel arm. The two phases of a trial were separated by a retention interval of 30 sec or of 4, 16 or 60 min. It was found that recall of the five free arm choices was related to the serial position of the previously visited arm. There was a significant recency effect at the 30-sec delay. With longer retention intervals this disappeared, and a significant primacy effect could be observed. In Experiment 2 the same animals were given forced arm entries during the study phase and delays of 30 sec or 4 or 16 min before the test phase. Again, there was a trend towards a recency effect after the shorter delays and a significant primacy effect after the 16-min interval. These results show that, in the recall of lists of spatial items, rats have serial position curves with primacy and recency effects, depending on the length of the retention interval.     

Primacy and recency effects in immediate free recall of sequences of spatial positions

This study evaluated the serial position curve based on free recall of spatial position sequences. To evaluate the memory processes underlying spatial recall, some manipulations were introduced by varying the length of spatial sequences (Exp. 1) and modifying the presentation rate of individual positions (Exp. 2). A primacy effect emerged for all sequence lengths, while a recency effect was evident only in the longer sequences. Moreover, slowing the presentation rate increased the magnitude of the primacy effect and abolished the recency effect. The main novelty of the present results is represented by the finding that better recall of early items in a sequence of spatial positions does not depend on the task requirement of an ordered recall but it can also be observed in a free recall paradigm.     

The effects of conformity on recognition judgements for emotional stimuli

Exposure to another’s account of a shared event can influence the content of an individual’s memory report. We examine whether the emotionality of the to-be-remembered information influences the likelihood that socially encountered post-event information is accepted into memory. Participants were exposed to positive, negative or neutral emotional pictures. Subsequently, they had to discriminate these pictures from new pictures in a ‘yes/no’ recognition decision either before or subsequent to a confederate providing misinformation, accurate or no information. Post-event information influenced participants’ responding in the recognition test. Effects were larger for participants viewing neutral items and persisted for these items on a subsequent private source monitoring test. These findings indicate that people rely more on information from others when encountering non-emotional compared to emotional items. We suggest that increased memory strength in conjunction with access to strong retrieval cues in the recognition test serves to shield emotional items from vulnerability to effects of memory conformity.     

A psychophysical investigation of language priming effects in two english-french bwguals

Abstract

This paper attempts to apply psychophysical methodology, usually reserved for the study of low-level perceptual proocsses, to the study of language priming effects in bilingual subjects. Previous research using more traditional psycholinguistic techniques has demonstrated that bilinguals find words in one language harder to recognise when immediately preceded by a word of their other language. In the present experiments, this result was shown to remain robust even after the subjects had become very familiar with the experimental stimuli, thus suggesting that it is a highly automatised, irrepressible effect. The basic language priming effect was shown to be dependent on the neighbourhood characteristics (number of orthographically similar words in each language) of the prime words, but mainly at short prime exposures (>60 msec). At longer durations (428 msec), only the language of the prime (English or French) played a role.     

On the psychophysical law and estimation procedures in psychophysical scaling

A general formulation of the power law is presented which has two special features: (1) negative exponents are admissible; and (2) the log law is a special limiting case. Estimation procedures, which provide joint estimates of the exponent and the absolute threshold, are derived for the direct ratio scaling methods. A solution is provided for theaveraging problem for ratio production and bisection scaling, two methods generating observations on the physical scale, and Monte Carlo methods are used to evaluate the resulting estimators.