Irrelevant relations and the active search for pattern structure in rat serial pattern learning

Hersh (Mem Cogn 2:771–774, 1974) investigated the role of irrelevant relations in college students’ pattern learning and performance for letter series completion problems. He created irrelevant relations in sequences by inserting items to make pattern structure ambiguous such that it was open to multiple interpretations during initial pattern processing. He reported irrelevant relations impaired humans’ performance more when placed at the beginning of patterns than at the end. However, once pattern structure was induced, irrelevant relations were not impairing. Here, we examined the impact on rat serial pattern learning of irrelevant relations positioned at the beginning or end of a serial pattern. Rats pressed levers in a circular array according to the same structured serial pattern, 123 234 345 456 567, where digits indicated the clockwise position of the correct lever. This structured serial pattern was interleaved with repeating responses on lever 2 to produce irrelevant relations at the beginning of the pattern (Beginning: 122232 223242 324252 425262 526272), on lever 6 to produce irrelevant relations at the end of the pattern (End: 162636 263646 364656 465666 566676), or on lever 8 to produce no irrelevant relations (No Irrelevant Relations: 182838 283848 384858 485868 586878. Irrelevant relations significantly retarded learning regardless of their placement within the pattern. However, irrelevant relations retarded learning significantly more when placed at the pattern beginning versus end. The results indicate that rats, like humans, process patterns from beginning to end.     

Sex differences in spatial ability and activity in two vole species (Microtus ochrogaster and M. pennsylvanicus)

The hypothesis that sex differences in maze learning result from sex differences in activity was tested with wild-caught prairie (Microtus ochrogaster) and meadow (M. pennsylvanicus) voles. For 38 voles error production and activity were simultaneously measured in a series of 7 symmetrical mazes. Repeated-measures analyses of variance (ANOVAS) examined species, sex, maze, and interaction effects for 3 dependent variables: errors, activity, and errors/activity. The pattern of significant effects was very different for the errors and activity ANOVAS, which suggests that differential activity cannot explain differential error rates. In contrast, the pattern of effects was very similar for errors and errors/activity ANOVAS, which suggests that controls for activity do not remove differences in error production. These results fail to support the activity hypothesis.     

Micro- and macro-adjustments of task set: activation and suppression in conflict tasks

Macro- and micro-adjustment of task set was studied using distributional analyses of performance data (reaction time and accuracy) obtained in a new experiment using the Simon task. Macro-adjustments involved the long-term strategic modifications in response to the relative probability of conflict trials, while micro-adjustment involved trial-by-trial modifications invoked by the commission of incidental errors. These adjustments were examined in detail in distributional analyses of RT and accuracy, which have been shown to be particularly useful in studying the role of activation and suppression in conflict tasks. The modification of behavioral strategies incurred by the commission of errors and by the relative probability that the irrelevant location corresponded to the incorrect response was found to involve a reduced location-driven direct response activation (as reflected in the early portions of the delta plots for accuracy) and a stronger selective suppression of that direct activation (as reflected in the delta plot slopes for RT). When the probability of conflict trials was high, the effects of irrelevant location were already precluded by macro-adjustment, so that error commission had no further micro-adjustment effect on subsequent behavior. These patterns were not disclosed by analysis of overall performance.     

Serial control of phonology in speech production: a hierarchical model

A dynamic oscillator-based model of the sequencing of phonemes in speech production (OSCAR) is described. An analysis of phoneme movement errors (anticipations, perseverations, and exchanges) from a large naturalistic speech error corpus provides a new set of data suitable for quantitative modeling and is used to derive a set of constraints that any speech-production model must address. The new computational model is shown to account for error type proportions, movement error distance gradients, the syllable-position effect, and phonological similarity effects. The model provides an alternative to frame-based accounts, serial buffer accounts, and associative chaining theories of serial order processing in speech.     

From Monroe to Moreau: an analysis of face naming errors.

Functional models of face recognition and speech production have developed separately. However, naming a familiar face is, of course, an act of speech production. In this paper we propose a revision of Bruce and Young's (1986) model of face processing, which incorporates two features of Levelt's (1989) model of speech production. In particular, the proposed model includes two stages of lexical access for names and monitoring of face naming based on a "perceptual loop". Two predictions were derived from the perceptual loop hypothesis of speech monitoring: (1) naming errors in which a (correct) rare surname is erroneously replaced by a common surname should occur more frequently than the reverse substitution (the error asymmetry effect); (2) naming errors in which a common surname is articulated are more likely to be repaired than errors which result in articulation of a rare surname (the error-repairing effect). Both predictions were supported by an analysis of face naming errors in a laboratory face naming task. In a further experiment we considered the possibility that the effects of surname frequency observed in face naming errors could be explained by the frequency sensitivity of lexical access in speech production. However, no effect of the frequency of the surname of the faces used in the previous experiment was found on face naming latencies. Therefore, it is concluded that the perceptual loop hypothesis provides the more parsimonious account of the entire pattern of the results.     

Focused attention in pervasively hyperactive children

This experiment was designed to investigate the hypothesized distractibility of hyperactive children in a focused attention task. Distractibility was defined in terms of Shiffrin and Schneider's model of focused attention as the ability to ignore irrelevant in favor of relevant information. Failure to inhibit processing of irrelevant information indicates a focused attention deficit. Task efficiency in all children decreased when irrelevant information was presented. The mean reaction time, within-subject variance of reaction time, and error percentage all increased compared with a nondistraction condition. Thus, the demands of focused attention, as formulated in the model, were measured optimally. Since hyperactives and controls did not differ significantly with respect to task efficiency in the distraction condition, a focused attention deficit in hyperactives was not demonstrated. The hyperactives did nevertheless make more errors and their responding was more variable than the controls. However, the difference in error percentages between hyperactives and controls was associated with the difference in IQ. It is speculated that the variable responding in hyperactives is caused by a less optimal state of performance unrelated to distractibility.The authors wish to thank L. Leertouwer for making the drawings. This research was supported by grants from the Netherlands Foundation for the Advancement of Pure Research (ZWO) and the Professor Duijker Fund.     

Origins of Paraphasias in Deep Dysphasia: Testing the Consequences of a Decay Impairment to an Interactive Spreading Activation Model of Lexical Retrieval

This study investigates an account of atypical error patterns within the framework of an interactive spreading activation model. Martin and Saffran (1992) described a patient, NC, whose error pattern was unusual for the occurrence of higher rates of form-related than meaning-related word substitutions in naming and the production of semantic errors in repetition. They proposed that NC′s error pattern could be accounted for by a pathologically rapid decay of primed nodes in the semantic-lexical-phonological network that shifts the probabilities of error outcome in lexical retrieval. In the present study, Martin and Saffran′s account was tested and supported in a series of simulations that reproduce essential features of NC′s lexical error pattern in naming and repetition. Also described here are the results of a longitudinal study of NC′s naming and repetition, which revealed a shift in relative lexical error rates toward a qualitatively normal pattern. This change in error pattern was simulated by assuming that recovery reflects resolution of the rapid decay rate toward normal levels. The patient data and computational studies are discussed in terms of their significance for the understanding of aphasic impairments and their implications for models of lexical retrieval.     

Intrusion errors in visuospatial working memory performance

This study tested the hypothesis that failure in active visuospatial working memory tasks involves a difficulty in avoiding intrusions due to information that is already activated. Two experiments are described, in which participants were required to process several series of locations on a 4 x 4 matrix and then to produce only the final location of each series. Results revealed a higher number of errors due to already activated locations (intrusions) compared with errors due to new locations (inventions). Moreover, when participants were required to pay extra attention to some irrelevant (non-final) locations by tapping on the table, intrusion errors increased. Results are discussed in terms of current models of working memory functioning.     

What aspects of vision facilitate haptic processing?

We investigate how vision affects haptic performance when task-relevant visual cues are reduced or excluded. The task was to remember the spatial location of six landmarks that were explored by touch in a tactile map. Here, we use specially designed spectacles that simulate residual peripheral vision, tunnel vision, diffuse light perception, and total blindness. Results for target locations differed, suggesting additional effects from adjacent touch cues. These are discussed. Touch with full vision was most accurate, as expected. Peripheral and tunnel vision, which reduce visuo-spatial cues, differed in error pattern. Both were less accurate than full vision, and significantly more accurate than touch with diffuse light perception, and touch alone. The important finding was that touch with diffuse light perception, which excludes spatial cues, did not differ from touch without vision in performance accuracy, nor in location error pattern. The contrast between spatially relevant versus spatially irrelevant vision provides new, rather decisive, evidence against the hypothesis that vision affects haptic processing even if it does not add task-relevant information. The results support optimal integration theories, and suggest that spatial and non-spatial aspects of vision need explicit distinction in bimodal studies and theories of spatial integration.     

Intrusion errors in visuospatial working memory performance

This study tested the hypothesis that failure in active visuospatial working memory tasks involves a difficulty in avoiding intrusions due to information that is already activated. Two experiments are described, in which participants were required to process several series of locations on a 4 × 4 matrix and then to produce only the final location of each series. Results revealed a higher number of errors due to already activated locations (intrusions) compared with errors due to new locations (inventions). Moreover, when participants were required to pay extra attention to some irrelevant (non-final) locations by tapping on the table, intrusion errors increased. Results are discussed in terms of current models of working memory functioning.     

Mimicking aphasic semantic errors in normal speech production: evidence from a novel experimental paradigm

Semantic errors are commonly found in semantic dementia (SD) and some forms of stroke aphasia and provide insights into semantic processing and speech production. Low error rates are found in standard picture naming tasks in normal controls. In order to increase error rates and thus provide an experimental model of aphasic performance, this study utilised a novel method- tempo picture naming. Experiment 1 showed that, compared to standard deadline naming tasks, participants made more errors on the tempo picture naming tasks. Further, RTs were longer and more errors were produced to living items than non-living items a pattern seen in both semantic dementia and semantically-impaired stroke aphasic patients. Experiment 2 showed that providing the initial phoneme as a cue enhanced performance whereas providing an incorrect phonemic cue further reduced performance. These results support the contention that the tempo picture naming paradigm reduces the time allowed for controlled semantic processing causing increased error rates. This experimental procedure would, therefore, appear to mimic the performance of aphasic patients with multi-modal semantic impairment that results from poor semantic control rather than the degradation of semantic representations observed in semantic dementia [Jefferies, E. A., & Lambon Ralph, M. A. (2006). Semantic impairment in stoke aphasia vs. semantic dementia: A case-series comparison. Brain, 129, 2132-2147]. Further implications for theories of semantic cognition and models of speech processing are discussed.     

The locus of location repetition latency effects.

We examined the processing locus (location vs. response) of location repetition effects in terms of the event [target (t) or distractor (d)] that initially occupied and then re-occupied the repeated location (i.e., t-to-t, t-to-d, d-to-t, d-to-d). Trials were presented in pairs (prime, then probe) and 2:1 location-to-response mappings were used. Generally, for all repetition conditions, perceptual processing at the repeated location itself was facilitated (location locus), while re-activated responses delayed output production (response locus). More specifically, perceptual facilitation observed for a repeated location was independent of the kind of processing (i.e., t or d) that occurred earlier, suggesting that it is not the labeling of locations as relevant or irrelevant that determines location repetition effects. Response production was significantly slowed only when a just-inhibited response had then to be executed, which supported the view that the spatial negative priming effect has a response locus.     

Sequential analysis of the numerical Stroop effect reveals response suppression

Automatic processing of irrelevant stimulus dimensions has been demonstrated in a variety of tasks. Previous studies have shown that conflict between relevant and irrelevant dimensions can be reduced when a feature of the irrelevant dimension is repeated. The specific level at which the automatic process is suppressed (e.g., perceptual repetition, response repetition), however, is less understood. In the current experiment we used the numerical Stroop paradigm, in which the processing of irrelevant numerical values of 2 digits interferes with the processing of their physical size, to pinpoint the precise level of the suppression. Using a sequential analysis, we dissociated perceptual repetition from response repetition of the relevant and irrelevant dimension. Our analyses of reaction times, error rates, and diffusion modeling revealed that the congruity effect is significantly reduced or even absent when the response sequence of the irrelevant dimension, rather than the numerical value or the physical size, is repeated. These results suggest that automatic activation of the irrelevant dimension is suppressed at the response level. The current results shed light on the level of interaction between numerical magnitude and physical size as well as the effect of variability of responses and stimuli on automatic processing.     

A critique of top-down independent levels models of speech production: Evidence from non-plan-internal speech errors

A number of speech errors are examined which are difficult to account for by top-down serial processing models of speech production which hove independent levels of processing. In particular, most of these errors are characterized by the presence of an interfering element which is external to the utterance under current construction. This paper has two main aims: to classify these errors, and to examine the constraints upon them. It is found that phonological similarity between the target and intrusion is a major determinant of error occurrence. The consequences for models of speech production are discussed in a framework consisting of the architecture and control structure of those models. A particular model to account for these data is proposed, consisting of a spreading activation lexical network.     

Selective perception without confounding contributions of decision and memory

Previous research has demonstrated that decision processes and short-term memory limitations contribute to the observed limitation in the span of apprehension in tachistoscopic experiments. The present study addresses the question of whether perceptual factors also contribute to this limitation. Observers were asked to indicate which of four target letters occurred in a four-item test display. The irrelevant background items were either highly confusable or completely nonconfusable with the target letters. The target detection task is designed to bypass short-term memory limitations. In order to eliminate differences in decision processing, the location of the target letter was indicated either slightly before or shortly after the display presentation. The indicator was either an arrow cue or a pattern mask. Performance decreased with increases in the delay of the arrow cue only when the background items were confusable. The pattern mask yielded standard masking functions, but performance with the nonconfusable background items improved more rapidly with increases in processing time than did performance with the confusable background items. These results conform to the hypothesis that attention operates at the perceptual stage of processing. The results were accurately described by a quantification of attentional effects in a general information processing model.     

Interactive processing among parts, configuration, and orientation of complex objects

The aim of the present study was to investigate whether the representation of parts and the configuration and orientation of complex objects were separate or interdependent. Participants were asked to match parts and configuration of novel 3-D objects with constant or varied features in irrelevant dimensions. The results of both Exp. 1 (sequential matching) and Exp. 2 (simultaneous matching) showed that both sensitivity and response time (RT) of part matching were influenced by whether the irrelevant configuration remained constant or varied. Both sensitivity and RT for configuration matching were affected by the variation of irrelevant parts in Exp. 2, but only sensitivity was affected in Exp. 1. These results demonstrated an interdependent pattern of representations of parts and relations but different interactive patterns in memory and perception. The results of Exp. 3 showed orientation dependency in a configuration-matching task but orientation invariance in a part-matching task. Consistent with a study done in 2000 by Edelman and Intrator, these results suggest an interactive processing between configuration and orientation but an independent processing between the parts and orientation.     

Response monitoring and expectancy in random serial RT tasks

Two different sequential patterns have been reported in serial reaction-time (RT) tasks with random stimulus sequences, depending on the response-to-stimulus interval (RSI). When RSI is short a first-order repetition effect and a higher order benefit-only pattern are found, and when RSI is long a cost-benefit pattern is observed. In a series of three experiments, we found that the patterns are not unique for spatial dimensions, and that the benefit-only pattern does not appear for irrelevant stimulus features. The cost-benefit pattern, on the other hand, can shift to irrelevant locations, but not to irrelevant colour. Distributional analyses of the sequential effects demonstrate that the first-order repetition effect can be dissociated from the higher order effects. The results are interpreted as support for the role of response monitoring in the development of the benefit-only pattern at short RSI, while the first-order repetition effect is explained as repetition priming. With a long RSI, the cost-benefit pattern is confirmed as a low-level subjective expectancy process, which is primarily controlled by stimulus location. The data clearly strengthen the support for three different processes generating sequential effects in random serial RT tasks.     

Short-term memory, working memory, and inhibitory control in children with difficulties in arithmetic problem solving

The relations between short-term memory, working memory, inhibitory control, and arithmetic word problem solution were studied in children who were poor in arithmetic problem solving (n = 23). The children were compared with a group of good problem solvers (n = 26), matched for vocabulary, age, and gender. The results corroborate the hypothesis of poor problem solvers' general deficit in inhibitory processes. They had lower scores and made more intrusion errors in a series of working memory tasks requiring inhibition of irrelevant information. The results showed that problem solving performance is related to the ability of reducing the accessibility of nontarget and irrelevant information in memory. Span tasks that imply passive storage of information showed that poor problem solvers were impaired when they have to retain numerical information, but they did not differ from children who did not have difficulty with mathematics when the material included words.     

Perceptual and attentional factors in encoding irrelevant spatial information

Numerous studies found superior performance when the irrelevant location of a stimulus and response location were corresponding than when they were not corresponding (Simon effect), suggesting that stimulus location is processed in an obligatory manner. The present study compared Simon effects from the location of a relevant (i.e., to-be-attended) object to those from the location of an irrelevant (i.e., to-be-ignored) object. In four experiments, participants were presented with a rectangular frame and a square, with the relevant object in green or red color and the irrelevant object in gray or white color. Participants’ task was to respond with a lateral keypress to the color of the relevant object, and we varied spatial correspondence between the location of the relevant or the irrelevant object and the response, respectively. Results consistently showed larger Simon effects from the location of the relevant than from the irrelevant object, even when the irrelevant object was made very salient. These results suggest that location processing is largely confined to relevant (i.e., attended) objects, stressing the role of attention shifts for location encoding.     

Difficulties in the control of irrelevant visuospatial information in children with visuospatial learning disabilities

This research tested the hypothesis that children's difficulties in visuospatial working memory (VSWM) may mirror difficulties found with verbal working memory tasks in other categories of children. Two experiments compared the number of correct responses and errors in groups of visuospatial learning disabled children (VSLD) and Controls who were engaged in an active task testing visuospatial working memory. Children were presented with sequences of positions on a 4x4 matrix and were subsequently asked to remember only the last position of each series. In the first Experiment, VSLD children showed greater difficulty in both recalling the last positions and avoiding the irrelevant non-final positions compared with Controls. In the second experiment children of different age groups (second-graders and fifth-graders) were also required to stress, by tapping on the table, the irrelevant positions whenever the experimenter pointed to a coloured cell. Results showed that the number of errors was greater in the VSLD children, and the pattern of errors differed with their grade. In particular, the increased activation of stressed locations produced an increase of correct responses, and a decrease of intrusion errors, except in the case of VSLD second-graders, who made a higher number of intrusions for stressed than for unstressed locations. Results confirm that children with VSLD show a specific deficit in active VSWM, and in particular, in the ability to avoid intrusion errors. In general, the control of irrelevant information appears critical for a successful use of VSWM.