As auditory displays become more common it is increasingly important to understand the perception of complex and dynamic auditory stimuli and how the information contained in the various dimensions of these stimuli influences performance. In the present study listeners made keypress responses to dynamic sound stimuli which started high or low in pitch and became higher or lower in pitch during each trial. The results showed that pitch and pitch change interacted in an asymmetrical manner, with pitch information intruding more on judgments of pitch change than vice versa. Neither pitch nor pitch change interacted with vertically arranged responses to produce the strong spatial S-R compatibility effects that were expected based on previous research and on descriptions of pitch in everyday language. Analytic versus holistic listening strategies or the physical location of the sounds may affect interactions of the stimuli and responses in this type of selective listening task.

Experiments reported here examined the effects of distributing practice during relearning. Specifically, they provide an initial test of the prediction by R. A. Bjork and C. O. Fritz (1994), based on the new theory of disuse (R. A. Bjork & E. L. Bjork, 1992), that spacing practice is not important for relearning. In Experiment 1a, the speed to respond to simple numeric multiplication problems was measured after subjects practiced the problems under three different relearning schedules: (1) A massed condition in which all of the practice on a specific problem occurred consecutively, (2) a spaced condition in which there was a uniform spacing of one intervening problem between each practice on a particular problem, and (3) an expanded condition in which the practice was spaced in an expanded fashion, such that first there were no intervening problems between practices, then there were 4 problems, followed by 8. No significant differences among these three conditions were found. In Experiment 1b, original learning on an analogous task, mental arithmetic involving letters rather than numbers, was performed under the same three learning schedules. A spacing effect was found under the original learning conditions of Experiment 1b. Experiment 2 was similar to Experiment 1a, except that the instructions placed more stress on accuracy in order to avoid problems associated with a speed/accuracy trade-off. As with Experiment 1a, there was no significant effect of condition. The results provide preliminary support for Bjork and Fritz's prediction regarding the distribution of practice during relearning. The findings are encouraging from a practical standpoint and support the notion that level of expertise is an important factor in research on long-term retention.

Speech error data and empirical studies indicate that the scope of planning is larger for semantic/syntactic than phonological form representations in speech production. R. Martin and colleagues have demonstrated that some patients show dissociable impairments in the retention of semantic and phonological codes. The effect of these STM deficits on speech production was investigated using phrase and sentence production paradigms which manipulated semantic and phonological factors of the words to be produced. The first four experiments used a phrase production paradigm in which subjects named pairs of pictures and words manipulated for categorical relatedness (Experiments 1 and 2) or frequency (Experiments 3 and 4). The findings suggested that subjects planned both lemmas in these phrases but only the initial lexeme. Planning two lemmas created difficulty (large categorical interference effects) for patients with semantic retention deficits but not for patients with phonological retention deficits, supporting the contention that the semantic retention buffer involved in word span tasks is involved in speech production planning. In Experiment 5, subjects produced sentences having the content words in separate phrases to describe the configuration of two pictures. Control subjects and patients with phonological retention deficits did not show interference from categorically related pictures suggesting that they did not plan the final lemma of the sentence before articulation. ML still showed a large interference effect which reversed to facilitation when the pictures remained on the screen during his response. It was suggested that ML is forced to plan multiple lemmas before the pictures disappear, but when the pictures remain in view he may plan in a phrase-by-phrase fashion. In Experiment 6, ML showed a large benefit in onset latency but not accuracy when he could describe pictures in a sentence compared to phrase format whereas EA showed no such benefit. SJD also showed a benefit in accuracy for sentences compared to phrases, but her errors were qualitatively different than those of ML. The findings suggest that semantic retention is critical for speech planning for constructions requiring that multiple lemmas be planned in advance, while phonological retention is less critical because of the smaller scope of planning at this level.

In Experiment 1, homophone and repetition priming were evaluated in 3 implicit memory tests. Homophone priming was comparable in size to repetition priming in the naming task, while reduced, but significant, homophone priming was obtained in the lexical decision and perceptual identification tasks. In Experiment 2, pseudohomophones (e.g., brane) were utilized as the distractor foils at test rather than pronounceable nonwords (e.g., terl). The homophone priming obtained in the lexical decision task in Experiment 1 was eliminated suggesting that phonological priming can be strategic. The role of orthography in homophone priming in the naming task was evaluated in Experiment 3. Homophone priming appears to depend upon the amount of orthographic overlap; orthographically dissimilar homophone pairs (e.g., bomb, balm) exhibited less homophone priming compared to similar pairs (e.g., bell, belle).

This study examined how attentional set mitigates attention capture by onsets occurring between known spatial locations. In Experiment 1 response times increased with the number of onsets that occurred. In Experiment 2 and 3 color was used instead of onset as the task relevant feature. Data collected at the keystroke-level showed delayed response times for keystrokes in only certain positions following an onset. Typing patterns were also found to affect the costs generated by the onsets, implying that task strategies mediated when onsets captured attention. Experiment 4 manipulated the cue types in a 2 phase spatial cuing task. Cues of the same type in both phases yielded faster responses, even though the blocked nature of the trials alerted participants to the upcoming cue type in each phase. This suggests that participants were unable to rapidly shift attentional set.

The performance of a highly literate subject, BS, was assessed on tests of short-term memory. He demonstrated a pattern of performance similar to that of patients having a phonological short-term memory deficit. His profile included an exaggerated phonological similarity effect for auditorily, but not visually presented materials, the absence of a recency effect, a reversed modality effect, and difficulty repeating non-words. In contrast to previously described phonological short-term memory patients, BS performed fairly normally in a foreign language learning task, though his acquisition rate was slower than that of control subjects. This finding is counter to current theory which suggests intact phonological short-term memory is necessary to learning of new phonological forms. Further investigation of BS's deficit suggested that his areas of preserved performance were the result of strategic reliance upon semantic, lexical or orthographic factors. Thus support is demonstrated for theories of short-term memory that propose multiple components contributing to short-term memory.

The suffix effect refers to the forgetting of the last few items of a just-spoken list caused by appending a nominally irrelevant item. Several theorists hold that rememberer strategy affects only the preterminal component of the suffix effect and on this basis they have advocated a two-component theory of the effect. This theory has received significant support from the finding that rendering list length unpredictable eliminates the preterminal component while having little if any effect on the terminal component. Contrary evidence is reported here. Specifically, a robust preterminal suffix effect is demonstrated in each of three experiments regardless of list length predictability. The discrepancy with the earlier finding might be due, in part at least, to a confound in the earlier research between knowledge of list length during presentation and knowledge of list length during recall. Other evidence taken as supporting two-component theory is reviewed and similarly found wanting.

The development of a good representation of data with an auditory display requires one to choose the type of transformation between the data and auditory information and the auditory dimension to use. There is good reason to believe that using two sound dimensions in a redundant way could enhance performance compared to using the dimensions individually (Kramer, 1996). Experiments 1 and 2 showed redundancy loss when using separable dimensions in a redundant way. Experiments 3A and 4A found that duration with pitch and rate of change in pitch appear to be integral based on the Garner task. Experiment 3B, 3C and 4B used duration and the redundant combination of duration and pitch versus rate of change in pitch for the representation of numerical values. However, there was no redundancy gain found. This result could be important for auditory display designers when deciding about auditory dimensions to use in displays.

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Latent inhibition (LI) is the attenuation in the acquisition of Pavlovian conditioning to a conditioned stimulus (CS) due to prior extensive exposure to that CS. It is assumed that LI is an animal model of attention in that animals learn to ignore the preexposed CS. The present series of experiments investigated the effects of selective serotonergic (5-HT) ligands known to increase 5-HT neurotransmission on LI using a conditioned emotional response (CER) procedure. In experiment 1, rats preexposed (PE) to 40 presentations of a tone CS acquired CER suppression more slowly than vehicle-treated nonpreexposed (NPE) animals, suggesting LI was obtained. Administration of 10 mg/kg fluoxetine (i.p.) did not influence CER acquisition in PE animals, suggesting that LI was not affected by fluoxetine. However, it was assumed that 40 CS presentations exerted a powerful LI effect, which might mask any effect of fluoxetine. Consequently, we assessed the effects of 5-HT ligands on LI following 10, rather than 40, CS preexposures. Under these conditions, both acute fluoxetine (experiment 2), and chronic (14 day) fluoxetine (experiment 3) administration, were found to augment LI. Experiment 4 suggested that acute administration of the 5-HT2 agonist DOI (2.5 mg/kg) also enhances LI. Experiment 5 revealed that 1 mg/kg 8-OH-DPAT did not influence LI, suggesting that postsynaptic 5-HT1a receptors are not involved in LI. These results suggest that enhancement of 5-HT neurotransmission enhance LI and that this effect is mediated, in part, through the 5-HT2 receptor subtype. The results are discussed within the context of the switching model of LI, which suggests that the effects of 5-HT are mediated through the modulation of the mesolimbic dopamine pathway.