No presente trabalho é apresentado o Teste de Omissões Voluntárias (Square-Skipping Test, SST), uma versão de papel e lápis da tarefa computadorizada do sinal inibitório. Na primeira parte do trabalho, são relatados estudos que utilizaram uma tarefa computadorizada do sinal inibitório com estímulos excitatórios e inibitórios apresentados visualmente em um procedimento lateralizado. As estratégias de esperar o sinal inibitório foram controladas com sucesso mediante o controle "on-line" da estabilidade dos tempos de reação ao sinal excitatório. Um dos objetivos foi elucidar algum possível fator comum subjacente ao desempenho na tarefa do sinal inibitório e no Teste da tarefa Dupla. Os tempos de reação ao sinal inibitório não foram afetados pela lateralização, enquanto que os tempos de reação ao sinal excitatório direito foram os mais rápidos. Esta vantagem, a qual parece envolver especialização hemisférica e comunicação interhemisférica, correlacionou com a perda no desempenho da tarefa de box-crossing quando combinada com a tarefa verbal no Teste da Tarefa Dupla. A diferença Parte B-menos-Parte A do Trail Making Test correlacionou com os tempos de reação simples. Os resultados também sugerem a associação entre o tempo de reação simples e funções executivas. Foi descartada uma assimetria no sentido do deslocamento da atenção entre hemicampos para explicar a vantagem dos tempos de reação ao sinal excitatório direito. O tempo de reação simples parece ser uma medida de capacidade executiva. A comparação do desempenho de adultos idosos e jovens, medido pela tarefa computadorizada, demostrou que o controle inibitório não foi afetado de forma significativa pela idade. Na segunda parte do trabalho, é apresentado o SST, o qual permite obter de forma prática e rápida, medidas da habilidade inibitória e outras capacidades executivas tais como a flexibilidade cognitiva, a atenção concentrada e a velocidade na busca visual. O SST foi validado mediante a comparação com o desempenho na tarefa computadorizada do sinal inibitório. A execução do SST requer marcar com ‘Xs’ quadradinhos alinhados em um caminho irregular impressos em uma folha A4 (Parte D), sendo que nas Partes A, B e C devem-se omitir alguns quadradinhos indicados. Na terceira tentativa do SST deve ser escrita a seqüência de dígitos ‘1, 2, 3’. A correlação com o teste computadorizado do sinal inibitório sugeriu que o controle inibitório seria medido pela Parte D preenchida com a seqüência de dígitos (Parte D3). A idade não afetou de forma significativa o desempenho na Parte D3. O fator idade parece afetar seletivamente o desempenho nas diferentes partes do SST; p. ex. na Parte A1, que correlacionou com o coeficiente de atenção concentrada do Teste de Toulouse-Pièron. Para evitar os efeitos da prática sobre o desempenho no SST, recomenda-se a execução do Teste da Tarefa Dupla antes da execução do SST, e de preferência na mesma sessão experimental.

The present study aims to contribute to the understanding of the inhibitory ability, within the framework of the neuropsychology. The objective was to develop a paper-and-pencil test to assess the ability to stop an action in a simple and rapid way. A computerized stop signal task was used to validate the test. In the first part of this work, studies that involved the computerized stop signal task are presented. The result of these studies allowed to raise some theoretical issues. The paper-and-pencil test is presented in the second part of this work. In the Experiment 1 the aim was to control experimentally the strategy of waiting for the stop-signal on a lateralized stop signal task, by means of an algorithm, which controlled, on-line, the variation of response latencies for the go-signal (GSRT). Thirty-four healthy volunteers participated in this study. The GRST of the group that performed the task without the algorithm were significantly higher than the GSRT of the group that performed the task with the algorithm, whereas the stop-signal reaction times did not reach significant differences between groups. This procedure provided more stable reaction times throughout the task, and shifted the probability of responding on stop-trials from 0.364 to 0.479. The Experiment 2 studied the relationship between reaction time, laterality, and executive functions were examined by employing two computerized tasks with lateralized visual stimuli. Simple reaction time (SRT) was correlated with the Part B-minus-A difference of Trail Making Test (TMT). No significant difference was found between left and right SRT. Reaction times for left go-signals of the Stop-task were longer than reaction times for right go-signals. The ratio of left go-signal-minus left SRT to right go-signal-minus-right SRT was correlated with the loss in the visuospatial component when it was combined with a concurrent verbal task in the Dual-Task Test. Results suggest association between SRT and executive functions, and the involvement of hemispheric specialization and interhemispheric transfer in both, the stop signal task and the Dual-Tasks Test. Results from Experiment 3 permit to discard the possibility that the observed right visual field advantage observed was due to the orienting of attention across hemifields. The left GSRT were significantly slower than right GSRT. The right GRST advantage was not due to an attentional shift between left and right visual hemifields. In the Experiment 4, the stopping ability of older people in the computerized stop task was explored. There were no significant differences between the stopping ability of older and younger adults. The Square-skipping Test (SST) a paper-an-pencil version of the stop signal computerized task. is described in the second part of this study. The SST is divided in four parts. The effect of the administration of the different parts of the SST was studied in Experiment 5. The results allow for the use of the four parts in the same trial, since there was no effect of order of administration. In Experiment 6 it was studied the effect of placing a digit sequence on the third trial of the test, instead of the X’s. It seems that a greater degree on the inhibitory ability is necessary to perform the task with the sequence "1, 2, 3", than with the sequence "3, 2, 1". Thus, the sequence "1, 2, 3" was used in the final version of the SST. The practice effects of the Dual-Task Test on the SST was studied in Experiment 7. The interaction Group x Trial showed a general decrease on the performance of participants without previous practice in the Dual-task Test, contrasting with the performance of participants with within-session practice, which showed a clear digit sequence load effect. The aim of Experiment 8 was to know possible aging effects in the performance of SST. A general decrease was observed in the performance of older adults compared with performance of young adults; the interaction Group x Trial showed that the slope of the curves were different. The performance in SST is significantly affected by age. Performance in SST correlated with performance in the stop signal and the SRT tasks, respectively. Performance in SST also correlates with TMT, with the visuospatial component of the mu index of the Dual-task and with the attention coefficient of the Toulouse-Pièron Test. The best predictor of the stopping ability was the performance on the Part D with the digit sequence (Part D3). Thus, SST seems to be a useful neuropsychological tool for the assessment of several executive functions, including the stopping ability, mental flexibility, speed for visual search and focused attention.