Semantic Memory

Recall decreases across a series of subspan immediate-recall trials but rebounds if the semantic category of the words is changed, an example of release from proactive interference (RPI). The size of the rebound depends on the semantic categories used and ranges from 0% to 95%. We used a corpus of novels to create vectors representing the meaning of about 40,000 words using the BEAGLE algorithm. The distance between categories and spread within categories jointly predicted the size of the RPI. We used a holo-graphic model for recall equipped with a lexicon of BEAGLE vectors representing the meaning of words. The model captured RPI using a hologram as an interface to bridge information from episodic and semantic memory; it is the first account of RPI to capture release at the level of individual words in categorized lists.

Changes in semantic memory are a controversial topic in research on cognitive decline in aging. In this study, we analyzed whether the semantic deficits in mild Alzheimer's disease (AD) reflect the information acquisition process, and whether the deficits are related to when the information was initially stored. We hypothesized that in the earlier stages of dementia, the ability to access semantic associative relations reflects the use of these associations during different developmental stages. Specifically, we asserted that Alzheimer's patients might be able to access the relations that are learned earlier in life for the longest amount of time compared to those that are learned later. In this study, 254 subjects were divided into four groups (child, adult, senior, and Alzheimer's patients groups) and were evaluated with an experimental semantic association task that incorporated five semantic associative relations that were used to compare performance by age group. An analysis of variance (ANOVA) 4 × 5 test showed a significant main group effect, F(3, 250) = 97.1, p < .001, and an associative relations effect, F(4, 1000) = 23.1, p < .001, as well as an interaction of Group × Associative Relations, F(12, 1000) = 8.5, p < .001. The results demonstrated that the semantic associative relations that were acquired in later developmental stages were less preserved in persons with mild AD (i.e., superordinate relation, p < .0001). On the contrary, the semantic relations acquired earlier in childhood were better preserved in persons with mild AD. Our results suggest that semantic impairment begins with difficulties in using the associative relations that link concepts together in the semantic memory of patients with mild AD dementia (and possibly in individuals with mild cognitive impairment).

Deterioration of semantic memory is one of the primary neuropsychological deficits caused by Alzheimer's disease (AD). In this study, we hypothesize that the breakdown of semantic memory in the mild-to-moderate stage of AD is due to the disruption of the semantic network that links the concepts. Furthermore, the loss of these links is not homogeneous through the semantic association categories (i.e., Superordinate, Contiguity, Part/Whole, Attribute, Function). Twenty-two subjects (11 patients with mild-to-moderate dementia and 11 control subjects matched on demographics) participated in the study. Both controls and patients with AD underwent extensive neuropsychological evaluation and three experimental tasks: (1) Naming Task, (2) Semantic Association Task, and (3) Semantic Knowledge Task. Results showed that: (1) The AD group was significantly different from the normal controls group in all the experimental tasks; (2) the Semantic Association Task was significantly worse than the other tasks; (3) for the AD group, the scores of the Function and Part/Whole association categories were higher than in the other categories; and (4) living stimuli were more impaired than nonliving. These data confirm prior research showing the semantic association is differently impaired in AD patients.

In this paper I examine the relation between the account of mechanical memory in Hegel’s Encyclopedia of the Philosophical Sciences and the speculative sentence in his Phenomenology of Spirit. Both accounts involve a transition to speculative thinking, a kind of thinking that is free from given images and representations.  By discussing them together I hope to illuminate how speculative thinking functions for Hegel and why it is important.  Specifically, I try to show how what Hegel calls mechanical memory can shed light on Hegel’s more familiar notion of the speculative sentence.  I also draw out implications of language and mechanical memory for what Hegel calls speculative thinking.  First, I examine Hegel’s account of language acquisition in the Encyclopedia, which involves an account of mechanical memory, to show how Hegel thinks the mind can produce a vehicle for thinking that it has produced both in form and content.  Second, I show how this vehicle of language works in the speculative sentence in the Phenomenology.

In this thesis, I examine the relation between the account of mechanical memory in Hegel’s Encyclopedia of the Philosophical Sciences and the speculative sentence in his Phenomenology of Spirit. Both accounts involve a transition to speculative thinking, a kind of thinking that is free from given images and representations. By discussing them together I hope to illuminate how speculative thinking functions for Hegel and why it is important. Specifically, I try to show how what Hegel calls mechanical memory can shed light on Hegel’s more familiar notion of the speculative sentence. I also draw out implications of language and mechanical memory for what Hegel calls speculative thinking.

Men (n = 31), women estrogen-users (n = 14), and women estrogen non-users (n = 41), whose average age was 72.1 +/- 5.6 years, were tested with a battery of psychological tests measuring verbal memory, visual memory, concentration and attention, language fluency and semantic memory, and mood. Plasma levels of testosterone (T), estradiol (E2), cortisol (CRT) and dehydroepiandrosterone-sulfate (DHEAS) were assessed by radioimmunoassay. The ratio of DHEAS to CRT was calculated to determine it's relationship to memory functioning. The men had higher T and DHEAS levels than both groups of women. Women estrogen-users had higher E2 levels than both men and estrogen non-users and the men had higher E2 levels and a higher DHEAS/CRT ratio than the estrogen non-users. There were no group differences in CRT levels. Men and estrogen-users had higher total (p < .01) and forward (p < .001) digit span scores compared with non-users. Women estrogen-users also had higher backward digit span scores than non-users (p < .05), while both groups of women performed better than men on category retrieval (p < .01). The implications of these findings with respect to hormonal influences on memory in elderly men and women are discussed.

Men (n = 31), women estrogen-users (n = 14), and women estrogen non-users (n = 41), whose average age was 72.1 +/- 5.6 years, were tested with a battery of psychological tests measuring verbal memory, visual memory, concentration and attention, language fluency and semantic memory, and mood. Plasma levels of testosterone (T), estradiol (E2), cortisol (CRT) and dehydroepiandrosterone-sulfate (DHEAS) were assessed by radioimmunoassay. The ratio of DHEAS to CRT was calculated to determine it's relationship to memory functioning. The men had higher T and DHEAS levels than both groups of women. Women estrogen-users had higher E2 levels than both men and estrogen non-users and the men had higher E2 levels and a higher DHEAS/CRT ratio than the estrogen non-users. There were no group differences in CRT levels. Men and estrogen-users had higher total (p < .01) and forward (p < .001) digit span scores compared with non-users. Women estrogen-users also had higher backward digit span scores than non-users (p < .05), while both groups of women performed better than men on category retrieval (p < .01). The implications of these findings with respect to hormonal influences on memory in elderly men and women are discussed.

Having the concept coffee involves knowing not only how coffee looks, smells, and tastes, but also how it relates to other things. We consider two types of conceptual relationships: (1) taxonomic, i.e., between entities that share multiple features (e.g. coffee–tea), and (2) thematic, i.e., what things ‘go together’ in an event (e.g. coffee–spoon). We first review data suggesting that taxonomic and thematic relations are supported by semantic ‘hubs’ in the anterior temporal lobe (ATL) and angular gyrus (AG), respectively. We then propose that the AG’s connectivity to hippocampal regions supports its sensitivity to episodic detail and hence the event structures and context-sensitivities characterizing thematic relations, and that ATL’s connectivity with perirhinal cortex, which supports discrimination, promotes taxonomic categorization. Finally, we discuss several reasons that labelling may be particularly critical for taxonomic relations, and propose that processing in ATL is influenced by labels because of connectivity with frontal language regions.

El estudio sobre los conceptos es un problema de antigua data que tiene sus inicios hace miles de años en la antigua Grecia. Sin embargo, hasta hace sólo menos de un siglo que los conceptos son estudiados desde sus bases cognitivas y neurológicas. Este artículo busca realizar un contraste entre el análisis filosófico sobre la naturaleza de los conceptos y los estudios psicológicos sobre memoria semántica. Para abordar el análisis filosófico del problema sobre los conceptos es necesario empezar por la teoría clásica de las definiciones, pasar por la teoría de prototipos y concluir con la teoría de los proxitipos. Para abordar los estudios psicológicos sobre la memoria semántica es necesario explorar los modelos tradicionales de red jerárquica y de activación propagada; y el nuevo modelo de red radial. Esto nos permitirá concluir con un punto de vista alrededor de la polémica de la naturaleza de los conceptos que se desarrolla entre Diana Pérez, que los concibe como habilidades, y Liza Skidelsky, que los concibe como representaciones.

We examine production of word definitions by people with probable Alzheimer's disease (pAD). In the first experiment, healthy young adults defined concrete, imageable nouns to provide a baseline of definitional ability. Analysis of these definitions identified the key defining features of each target item. In the second experiment, pAD participants and elderly controls produced definitions of the same items. In the third experiment, healthy young participants rated the adequacies of these definitions. Although as expected the pAD participants produced fewer good definitions than the other two groups, most of their responses still contained some relevant information. pAD definitions contained fewer pieces of information and the information they produced was more tangential to the primary concept than that provided by the young or elderly participants. We identify two possible explanations in semantic loss and metalinguistic impairment. We consider metalinguistic impairment to provide the more plausible explanation of pAD patients' definitional performance.

While it is well documented that autobiographical memory (ABM) recall is affected in Posttraumatic Stress Disorders (PTSD), less is known about the cognitive mechanisms that underlie this pattern. This paper presents two research studies which investigated the role of thought suppression in the recall of ABMs. Study 1 assessed the role of thought suppression as a correlate of ABM retrieval in an undergraduate student sample (n=50). The results showed that higher levels of trait thought suppression were significantly correlated with faster recall of negative episodic memories as well as reduced recall of personal semantic memories. Thought suppression remained as a significant predictor of ABM recall, even when the participants' levels of depression and post-traumatic stress reactions were considered. Study 2 investigated the causal effects of thought suppression on ABM recall. 64 undergraduate students were shown a negative video clip and were asked either to suppress any thought of the video or simply to monitor their thoughts immediately thereafter. Results showed that suppression directly led to significantly enhanced negative episodic ABM recall, as well as a significantly reduced ability to recall personal semantic memories.

Working and strategic memory were examined in unmedicated patients with Parkinson's disease who had neither depression nor dementia. The patients, relative to control participants, had reduced working memory spans for verbal and arithmetic material. They also had impairment on ...

The comprehension of metaphors involves the ability to activate a broader, more flexible set of semantic associations in order to integrate the meanings of the weakly related parts of the metaphor into a meaningful linguistic expression. Previous findings point to a relation between levels of creativity and efficiency in processing metaphoric expressions, as measured by reaction times (RTs) and error rates. Furthermore, recent studies have found that more creative individuals exhibit a relatively more flexible semantic memory structure compared to less creative individuals, which may facilitate their comprehension of novel metaphors. In the present study, lower and higher creative individuals performed a semantic relatedness judgment task on word pairs. These word pairs comprised
four types of semantic relations: novel metaphors, conventional metaphors, literal word pairs, and meaningless word pairs. We hypothesized that the two groups will perform similarly in comprehending the literal, unrelated, and the conventional metaphoric word pairs. However, with respect to novel metaphors, we predicted that higher creative individuals will demonstrate better performance compared to lower creative individuals,
as indicated by smaller RTs and more accurate responses. Our main finding shows that higher creative individuals were faster in comprehending both types of metaphors, conventional and novel, compared to lower creative individuals. Furthermore, higher creative individuals were significantly more accurate than lower creative individual only in comprehending novel metaphors. The findings are discussed in light of previous findings regarding the relation between metaphor comprehension, semantic memory, and creativity.

We carried out an fMRI study with a twofold purpose: to investigate the relationship between networks dedicated to semantic and visual processing and to address the issue of whether semantic memory is subserved by a unique network or by different subsystems, according to semantic category or feature type. To achieve our goals, we administered a word-picture matching task, with within-category foils, to 15 healthy subjects during scanning. Semantic distance between the target and the foil and semantic domain of the target-foil pairs were varied orthogonally. Our results suggest that an amodal, undifferentiated network for the semantic processing of living things and artifacts is located in the anterolateral aspects of the temporal lobes; in fact, activity in this substrate was driven by semantic distance, not by semantic category. By contrast, activity in ventral occipito-temporal cortex was driven by category, not by semantic distance. We interpret the latter finding as the effect exerted by systematic differences between living things and artifacts at the level of their structural representations and possibly of their lower-level visual features. Finally, we attempt to reconcile contrasting data in the neuropsychological and functional imaging literature on semantic substrate and category specificity.