Academic journal article The Spanish Journal of Psychology

The Semantic Component of the Evoked Potential of Differentiation

Academic journal article The Spanish Journal of Psychology

The Semantic Component of the Evoked Potential of Differentiation

Article excerpt

This work analyzes data from recordings of (occipital and temporal) cortical evoked potentials (called evoked potentials of differentiation (EPD) occurring in humans in response to an abrupt substitution of stimuli. As stimuli we used three groups of words: the names of the ten basic colors taken from Newton's color circle; the names of seven basic emotions forming Shlossberg's circle of emotions; and seven nonsense words comprised of random combinations of letters. Within each group of word stimuli we constructed a matrix of the differences between the amplitudes of mid-latency components of EPD for each pair of words. This matrix was analyzed using the method of multidimensional scaling. As a result of this analysis we were able to distinguish the semantic and configurational components of EPD amplitude. The semantic component of EPD amplitude was evaluated by comparing structure of the data obtained to the circular structures of emotion and color names. The configurational component was evaluated on the basis of the attribute of word length (number of letters). It was demonstrated that the semantic component of the EPD can only be detected in the left occipital lead at an interpeak amplitude of P120-N180. The configurational component is reflected in the occipital and temporal leads to an identical extent, but only in the amplitude of a later (N180-P230) component of the EPD. The results obtained are discussed in terms of the coding of categorized, configurational, and semantic attributes of a visual stimulus.

Keywords: evoked potential of differentiation, multidimensional scaling, semantic component of EPD, visual categorization

Este trabajo analiza datos de registros (occipitales y temporales) de potenciales corticales evocados (llamados potenciales de diferenciación evocados-EPD) que ocurren en humanos como respuesta a una sustitución abrupta de estímulos. Como estímulos, se emplearon tres grupos de palabras: los nombres de los diez colores básicos tomados del círculo de color de Newton; los nombres de las siete emocionas básicas que forman el círculo de emociones de Shlossberg; y siete pseudo-palabras formadas por combinaciones de letras al azar. Para cada grupo de palabras-estímulo construimos una matriz de las diferencias entre las amplitudes de los componentes en la mitad de la latencia del EPD para cada pareja de palabras. Se analizó esta matriz con el método del escalonamiento multidimensional. Como resultado de este análisis, pudimos distinguir los componentes semánticos y configuracionales de la amplitud EPD. El componente semántico de la amplitud EPD se evaluó comparando la estructura de los datos obtenidos con las estructuras circulares de la emoción y de los nombres de los colores. El componente configuracional se evaluó mediante el atributo de la longitud de la palabra (número de letras). Se demostró que el componente semántico del EPD sólo puede detectarse en el electrodo occipital izquierdo en una amplitud inter-pico de P120-N180. El componente configuracional se refleja en los electrodos occipitales y temporales de forma idéntica, pero sólo en la amplitud de un componente más tardío (N180-P230) del EPD. Los resultados obtenidos se comentan en términos de la codificación de los atributos categorizados, configuracionales y semánticos de un estímulo visual. .

Palabras clave: potencial de diferenciación evocado, escalonamiento multidimensional, componente semántico del EPD, categorización visual

The spoken or written word, as a linguistic category, is very weakly linked to the physical characteristics of a stimulus word. Moreover, the semantic attributes of a word are only slightly liked with the configurational characteristics of the word-stimulus. Changes in font or orientation of letters, which can radically alter the geometric shape of a word, have no effect on the perception of its meaning. Given this isolation of the semantic attributes of a word from its physical features, special research interest accrues to the question of whether it is possible to specify the electrical brain activity related to this highly abstract feature of word stimuli. …

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