Declining object recognition performance in Semantic Dementia - a case for stored visual object representations

The role of the semantic system in recognising objects is a matter of debate. Connectionist theories argue that it is impossible for a participant to determine that an object is familiar to them without recourse to a semantic hub; localist theories state that accessing a stored representation of the visual features of the object is sufficient for recognition. We examine this issue through the longitudinal study of two cases of Semantic Dementia, a neurodegenerative disorder characterised by a progressive degradation of the semantic system. The cases in this paper do not conform to the "common" pattern of object recognition performance in Semantic Dementia described by Rogers et al (2004b), and show no systematic relationship between severity of semantic impairment and success in object decision. We argue that this data is inconsistent with the connectionist position but can be easily reconciled with localist theories that propose stored structural descriptions of objects outside of the semantic system

Naming acronyms : the influence of reading context in skilled reading and surface dyslexia

Background: Within dual route models of reading, words with regular spelling to sound correspondences can be read successfully using lexical or non-lexical reading processes. Research has indicated that which of these pathways is used is influenced by the other items that form the presentation context. We extend these findings using acronym stimuli as targets, presenting them in contexts designed to cue reading through grapheme phoneme conversion or letter naming. Method: In experiment 1, undergraduate participants (n = 30) read aloud stimuli presented onscreen. Response times and accuracy for target acronyms ambiguous in their print to pronunciation conversion (e.g. HIV versus NASA) were compared between two contexts. In one condition the majority of items were unambiguous acronyms (e.g. BBC). In the second condition, the non-target items were regular words (e.g. CAT). Experiment 2 administered the same reading task to a single case of semantic dementia. Results: A significant interaction between presentation context and acronym pronunciation was observed, such that responses were faster and more accurate to items that were pronounced in the same way as the majority of other stimuli in the list. Similar, though more dramatic, context effects were observed in a case of semantic dementia. Conclusions: We argue that context effects are pervasive in reading research and that presentation context should be considered when interpreting future findings, particularly in cases of aphasia and dyslexia.</p

Intranasal Inhalation of Oxytocin Improves Face Processing in Developmental Prosopagnosia

Developmental prosopagnosia (DP) is characterised by a severe, lifelong impairment in face recognition. Little work has attempted to improve face processing in these individuals, but intriguingly, recent evidence suggests oxytocin can improve face processing in both healthy participants and individuals with autism. This study examined whether oxytocin could also improve face processing in individuals with DP. Ten adults with the condition and 10 matched controls were tested using a randomized placebo-controlled double-blind within-subject experimental design (AB-BA). Each participant took part in two testing sessions where they inhaled 24IU of oxytocin or placebo spray and completed two face processing tests: one assessing face memory and the other face perception. Results showed main effects of both participant group and treatment condition in both face processing tests, but the two did not interact. Specifically, the performance of DP participants was significantly lower than control performance under both oxytocin and placebo conditions, but oxytocin improved processing to a similar extent in both groups

The Influence of Psycholinguistic Variables on Articulatory Errors in Naming in Progressive Motor Speech Degeneration

We describe an analysis of speech errors on a naming task in a man with progressive speech degeneration. Early assessment indicated naming impairments with no significant phonological or semantic impairment. To examine naming and the factors that influence speech errors, we selected 210 words varying in lexical and phonetic variables and conducted logistic regression analysis on speech error types. No significant naming errors were found. The only significant predictor of articulation errors was phonemic length and the only error type predicted was phone omissions. Results suggest that the sound omissions in naming are caused by motor speech impairment unrelated to lexical factors

How to get by with half a loop - An investigation of visual and auditory codes in a case of impaired phonological short-term memory (pSTM).

In the field of cognitive neuropsychology of phonological short-term memory (pSTM), a key debate surrounds the issue of how impairment on tasks deemed to tap this system imply a dissociable phonological input and output buffer system, with the implication that impairments can be fractionated across disruption to separate functional components (Nickels, Howard & Best, 1997). This study presents CT, a conduction aphasic who showed no impairment on basic auditory discrimination tasks, but had very poor nonword repetition. Clear-cut examples of such cases are very rare (see Jacquemot, Dupoux & Bachoud-Levi, 2007), and we interpret the case with reference to a pSTM model that includes input and output buffers. The dissociation between performance on auditory phonological tasks and visual phonological tasks we interpret as consistent with disruption to the link from input buffer to output buffer without concurrent damage to connections from output to input. Previous research has also shown that patients with impairments of pSTM can make visual confusions with orthographically presented items in tasks seeking to tap this mechanism (Warrington & Shallice, 1972), which might stem from having an incomplete pSTM loop. In light of this we examined whether CT's ability on tests of ISR was affected by visual orthographic similarity among list items, and this is indeed what we observed. On balance then, CT's overall profile is considered best interpreted with respect to a dual buffer pSTM model (e.g., Vallar & Papagno, 2002). [Abstract copyright: Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

Recognition memory in developmental prosopagnosia: electrophysiological evidence for abnormal routes to face recognition

Dual process models of recognition memory propose two distinct routes for recognizing a face: recollection and familiarity. Recollection is characterized by the remembering of some contextual detail from a previous encounter with a face whereas familiarity is the feeling of finding a face familiar without any contextual details. The Remember/Know (R/K) paradigm is thought to index the relative contributions of recollection and familiarity to recognition performance. Despite researchers measuring face recognition deficits in developmental prosopagnosia (DP) through a variety of methods, none have considered the distinct contributions of recollection and familiarity to recognition performance. The present study examined recognition memory for faces in eight individuals with DP and a group of controls using an R/K paradigm while recording electroencephalogram (EEG) data at the scalp. Those with DP were found to produce fewer correct “remember” responses and more false alarms than controls. EEG results showed that posterior “remember” old/new effects were delayed and restricted to the right posterior (RP) area in those with DP in comparison to the controls. A posterior “know” old/new effect commonly associated with familiarity for faces was only present in the controls whereas individuals with DP exhibited a frontal “know” old/new effect commonly associated with words, objects and pictures. These results suggest that individuals with DP do not utilize normal face-specific routes when making face recognition judgments but instead process faces using a pathway more commonly associated with objects

Prefixes repel stress in reading aloud: Evidence from surface dyslexia

This study examined the importance of prefixes as sublexical cues for stress assignment during reading aloud English disyllabic words. In particular, we tested the hypothesis that prefixes repel stress (Rastle & Coltheart, 2000) by investigating the likelihood with which patients with surface dyslexia assign second-syllable stress to prefixed words. Five such patients were presented with three types of disyllabic words for reading aloud: 'regular' prefixed words with weak-strong stress pattern (e.g., remind); 'irregular' prefixed words with strong-weak stress pattern (e.g., reflex); and non-prefixed words with strong-weak stress pattern (e.g., scandal). Results showed that all five patients frequently regularized the strong-weak prefixed words by pronouncing them with second syllable stress. These regularization errors provide strong evidence for the functional role of prefixes in stress assignment during reading. Additional computational simulations using the rule-based algorithm for pronouncing disyllables developed by Rastle and Coltheart (2000) and the CDP++ model of reading aloud (Perry et al., 2010) allowed us to evaluate how these two opponent approaches to reading aloud fare in respect of the patient data.15 page(s

Do individual differences in face recognition ability moderate the other ethnicity effect?

Individuals are better at recognizing faces from their own ethnic group compared with other ethnicity faces—the other-ethnicity effect (OEE). This finding is said to reflect differences in experience and familiarity to faces from other ethnicities relative to faces corresponding with the viewers' ethnicity. However, own-ethnicity face recognition performance ranges considerably within a population, from very poor to extremely good. In addition, within-population recognition performance on other-ethnicity faces can also vary considerably with some individuals being classed as “other ethnicity face blind” (Wan et al., 2017). Despite evidence for considerable variation in performance within population for faces of both types, it is currently unclear whether the magnitude of the OEE changes as a function of this variability. By recruiting large-scale multinational samples, we investigated the size of the OEE across the full range of own and other ethnicity face performance while considering measures of social contact. We find that the magnitude of the OEE is remarkably consistent across all levels of within-population own- and other-ethnicity face recognition ability, and this pattern was unaffected by social contact measures. These findings suggest that the OEE is a persistent feature of face recognition performance, with consequences for models built around very poor, and very good face recognizers