Developing the components of visuo-spatial working memory.

Recently, the theoretical perspective on visuo-spatial working memory has encompassed a two component framework, one an active spatial component and the other a passive visual component. However, this framework has been continually developed since it was originally put forward and its component parts subject to considerable revision. Within this changing theoretical context, empirical evidence will be presented detailing the importance of the dual task approach to the further description of visuo-spatial working memory.

Young and older participants were tested on a decision-making task that manipulated payoffs (avoidance, approach, and neutral). From each age group 17 participants were tested in each payoff group (102 participants in total). The data showed that relative to the neutral group, the young participants were cautious in the avoidance group, but decision behaviour did not change in the approach group. In contrast, the older participants did not change their decision behaviour in either the approach or the avoidance payoff groups. The findings are discussed in terms of motivational and cognitive factors involved in decision-making.

Similarity and Categorisation: Neuropsychological Evidence for a Dissociation

Roberson, D., Davidoff, J. & Braisby, N. Similarity and Categorisation: Neuropsychological Evidence for a Dissociation in Explicit Categorisation Tasks. Cognition (in press)

The Role of attention in motor and other recovery after brain damage

Native English or Italian speakers named object pictures or read aloud their names. Regression analyses of mean correct RTs involved a range of visual, orthographic, semantic and phonological predictors. Reading was faster than naming, and English groups were faster than Italian. Age of acquisition emerged as significant in all four experiments, with early-learned words being produced faster than later-learned words in both naming and reading. Other factors (e.g.,frequency, name agreement) were significant in some but not all analyses. The results will be discussed in terms of cognitive models of naming and reading in the two languages.

The influence of initial coarse-scale information in word-recognition.

We compared recognition performance of familiar letter strings (words) and unfamiliar letter strings (non-words) for targets preceded by briefly presented filtered strings. The filters disrupt the internal information contained in a word but maintain the low spatial frequency parameters of the string. The primes were filtered versions of either target strings (congruent) or strings differing by one letter (incongruent). Word recognition was superior for congruent filtered primes compared to the incongruent controls. Despite the lack of detailed, high spatial frequency information, relevant information is extracted from these primes to facilitate word recognition. Implications for theories of word recognition will be discussed.

Configural Information Contributes More to Object Representation than Featural Information

To test the relative contributions of configural and featural information during visual processing, 32 participants performed a forced-choice task. They first viewed an object for 275 ms, and then had to decide which of two stimuli matched it. In half the trials the stimuli were complete pictures, and in the other half they were only the identifying features. Response time and error rate both showed an advantage when the stimuli were complete pictures, suggesting a greater contribution from configural information. This advantage was greater for meaningful objects than it was for non-meaningful objects.

Crossmodal Attention

Four experiments investigated primacy effects in free recall using the overt rehearsal methodology. The increased primacy effects associated with a slow presentation rate (Experiment 1) and high frequency words (Experiment 2) were found mainly to be due to the increased rehearsal of early list items to later (recency) serial positions. Experiment 3 showed that a filled distractor interval affected the recall of items in recency but not primacy positions. Experiment 4 found that primacy was reduced and recency was increased when rehearsal was constrained to current items, for immediate and delayed recall, suggesting competition occurred between recency and primacy items.

Reversed cross-modal attenuation in word stem completion

A major prediction of transfer appropriate processing (TAP), consistently supported in the literature, is that re-instatement of modality at test produces the maximum priming facilitation, irrespective of modality type, and that a change of modality between study and test significantly attenuates priming. We report data showing that this pattern does not always hold. Using a novel stem presentation in an auditory word stem completion task, the standard pattern was reversed. That is, auditory cross modal priming was significantly higher than within modality priming. This finding was subseqeuntly replicated using different participants and materials. Reversal of cross modal attenuation challenges the re-instatement assumption of TAP theory and suggests that there may be compatible and interactive modality factors which facilitate cross modal compared to within modality priming.

Connectionist modelling of English past tense formation in Williams Syndrome.

Bromberg et al. (1994) and Clahsen and Almazan (1998) have argued that in past tense formation, people with Williams Syndrome show a dissociation between 'intact' grammatical abilities (regular verbs) and impaired lexical memory (irregular verbs). Pinker (1991) has argued that this phenotypic pattern supports an innate dual-route mechanism for inflectional morphology. We present a connectionist model of past tense formation in Williams Syndrome, which develops under atypical conditions and which demonstrates both delayed acquisition and a selective deficit for irregular verbs. We argue that the use of developmental disorders may be an inappropriate way to attempt to fractionate the normal language system, since abnormally developing systems are not normal systems with specific deficits, but qualitatively different systems (Karmiloff-Smith, 1998). We report on investigations of the relation of endstate deficits and developmental deficits within the model.

Cognitive development and ADHD in children born <32 weeks gestation

Recent improvements in rates of survival for pre-term infants has increased the interest in their development at school (Cooke, 1996). A geographically defined cohort, of 137 children born < 32 weeks gestation were compared at age seven to, 102 full-term control children. The WISC-II (Wechsler, 1992) and the Conners' Teacher Behaviour Rating Scale (Conners, 1997) were used to assess cognitive development and ADHD respectively. Fifteen percent of pre-term children and 1% of controls had full-scale IQ scores < 2 SD below the mean. ADHD was diagnosed in 24% of the pre-term children and 4% of controls. Future research needs to develop intervention programs, aimed at reducing these impairments.

S-R compatibilty effects in mental representations

The present paper provides for stimulus-response (S-R) compatibility effects in spatial mental representations. In three experiments participants learned an environment (university campus) through navigation (Experiment 1), or were presented with a map of an environment (Experiments 2 and 3), and then responded by relying on their long-term memory (mental representation) of the learned information. S-R compatibility effects were found in the experiments. For example, left responses to landmarks located to the left of the participant’s imagined heading were faster than right responses to the same landmarks. The findings have important implications for our understanding of the concept of mental representation.

The irrelevant sound effect: Interference by process or content?

Irrelevant sound disrupts serial recall, particularly if the sound changes in composition. Typically, repeated sounds produce less disruption than changing sounds. Increasing the rate of presentation of alternating tones well separated in pitch increased disruption, but only up to a point; at the fastest rates of presentation the degree of disruption of serial recall decreased significantly. This result can be accounted for by the tendency, at fast rates of presentation, for tones to separate into two streams made up of repeated tones. The pattern of results can be explained by the extent to which the process of seriation involved in the deliberate rehearsal of the to-be-remembered list clashes with that emerging from the pre-attentive organisation of the irrelevant sound into streams. These findings offer further support for the view that interference is based on similarity of process rather than similarity of content of the irrelevant sound and the to-be-remembered material.

A functional dissociation between two modes of classification in implicit learning

Participants can transfer grammatical knowledge acquired implicitly in one vocabulary to sequences in another vocabulary (new sequences are classified as grammatical or not). We present two experiments that find differences in sensitivity to sequential dependencies between repeating vocabulary elements (repetition structure) and sensitivity to dependencies between non-repeating elements (bigram information), in both the same vocabulary as training and in a novel one. Varying the strength of the dependencies between repeating and non-repeating elements provides a functional dissociation between these two modes of classification. These data have implications for models of implicit grammar learning which assume the representation of individual bigrams.

On-line Lexical Processing in Specifically Language Impaired and Normally Developing Children

An auditory-auditory lexical decision task assessed the effects that related primes had on lexical access of target words for SLI subjects (age 11:1 to 18:0) and normally developing children matched on language (age 6:11 to 9:7) or age. For all groups, semantically related nouns and morphologically related lexical verbs significantly facilitated lexical access, whereas phonologically related nouns and morphologically related auxiliary verbs had little facilitative effect. Regular and irregular morphology did not differentially affect lexical access. Word frequency affected the SLI subjects and younger LA controls, but not the older controls. The SLI subjects' auditory lexical processing and access was not slower than or significantly different from normally developing children, even for auxiliary verbs. Overall, the findings suggest that this task may be primarily tapping semantic associations rather than morphological relations. We discuss the methodological and theoretical issues raised by this study, and examine the implications for theories of normal and impaired language acquisition.

Autobiographical delusions in Alzheimer's disease may reflect episodic memory failure

It has been suggested that delusions in Alzheimer's disease (AD) arise fromfocal brain dysfunction and their content may reflect failure of the cognitive mechanism associated with the dysfunctional area. We investigated neuropsychological and blood flow profiles of AD patients with autobiographical delusions, with other delusions and without delusions. Findings show that only AD patients with autobiographical delusions have a selective deficit in the right frontal lobe and their neuropsychological profile show a greater deficit in episodic memory and executive functions tasks. We argue that delusion content is determined by episodic retrieval failure arising from right frontal dysfunction.

The veracity and consistency of flash-bulb memories

People report vivid memories of the circumstances in which they heard news which is surprising, of consequence, and which causes emotional arousal. To investigate so named ‘flashbulb memories’ (Brown & Kulik, 1977) of the circumstances in which people heard of the death of the Princess of Wales, accuracy and consistency of recall was looked at over various time intervals and number of repeated recalls. The results show some subtle changes in memory occurring over time. However, there is also strong evidence of sustained ‘flashbulb memories’ regardless of number repetitions, passage of time since the event and the consequentiality, emotional arousal and personal importance of the event to participants.

Posters

Previous research indicates that word length affects the recognition of briefly presented words projected to the left visual field (LVF), but not the right visual field (RVF). It has been proposed that this finding reflects parallel processing by the left hemisphere and serial processing by the right hemisphere (Ellis & Young, 1985). However, such research may be contaminated by non-central fixations and sophisticated guesswork. The current study examined whether the RVF advantage prevailed when these problems were overcome by using an objective method of ensuring central fixation and a two-alternative forced choice procedure (known as the Reicher-Wheeler task), which suppresses the influence of sophisticated guesswork. The findings provide little support for the parallel / serial distinction previously drawn between the way in which the hemispheres process words.

Memory Span for Pantomimed Movements