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Richard A Block

Publications and source records attributed to Richard A Block.

6 recordsLinked to original sources
PubMed2006

A Cartesian reflex assessment of face processing.

Commands to blink were embedded within pictures of faces and simple geometric shapes or forms. The faces and shapes were conditioned stimuli (CSs), and the required responses were conditioned responses, or more properly, Cartesian reflexes (CRs). As in classical conditioning protocols, response times (RTs) were measured from CS onset. RTs provided a measure of the processing cost (PC) of attending to a CS. A PC is the extra time required to respond relative to RTs to unconditioned stimulus (US) commands presented alone. They reflect the interplay between attentional processing of the informational content of a CS and its signaling function with respect to the US command. This resulted in longer RTs to embedded commands. Differences between PCs of faces and geometric shapes represent a starting place for a new mental chronometry based on the traditional idea that differences in RT reflect differences in information processing.

Adult↗
PubMed2005

Effects of caffeine on prospective duration judgements of various intervals depend on task difficulty.

The effects of caffeine on prospective duration judgements were investigated in two double-blind placebo-controlled experiments. After taking either 200 mg of caffeine or a placebo, participants performed a task that demanded considerable attention, driving a car in a simulator (Experiment 1) or a task that demanded relatively little attention, watching a videotaped scene from a driven car (Experiment 2). Each participant made duration judgements of three target intervals: 15 s, 60 s and 300 s. Actively driving participants in the caffeine condition judged it as shorter than did those in the placebo condition. Caffeine had no effect on duration judgements following passive viewing. When people must perform a relatively difficult task, caffeine causes participants to allocate relatively more of their attentional resources to the task and relatively less to duration timing. Although caffeine may increase the pacemaker rate of an internal clock (via dopamine D(1) agonism), when external events are attention-demanding, caffeine mainly influences the relative allocation of attention to external events or to time (via dopamine D(2) agonism) in cerebral areas subserving the executive control of attention.

Adult↗
PubMed2004

Prospective and retrospective duration judgments: an executive-control perspective.

Most theorists propose that when a person is aware that a duration judgment must be made (prospective paradigm), experienced duration depends on attention to temporal information, which competes with attention to nontemporal information. When a person is not aware that a duration judgment must be made until later (retrospective paradigm), remembered duration depends on incidental memory for temporal information. In the present article we describe two experiments in which durations involved with high-level, executive-control functions were judged either prospectively or retrospectively. In one experiment, the executive function involved resolving syntactic ambiguity in reading. In another experiment, it involved controlling the switching between tasks. In both experiments, there was a unique cost to the operation of control high-level, executive functions which was manifested by prospective reproductions shortening a finding that supports an attentional model of prospective timing. In addition, activation of executive functions produced contextual changes that were encoded in memory and resulted in longer retrospective reproductions, a finding that supports a contextual-change model of retrospective timing. Thus, different cognitive processes underlie prospective and retrospective timing. Recent findings obtained by some brain researchers also support these conclusions.

Animals↗
PubMed2003

Effect of caffeine on prospective and retrospective duration judgements.

The effects of caffeine on prospective and retrospective duration judgements were evaluated in a double-blind placebo-controlled experiment. After taking either 200 mg caffeine or a placebo, participants touched a 17-sided polygon for 15 s. Then they verbally estimated the number of angles and the duration. Participants in the prospective group were told in advance they would be making a duration estimate, whereas those in the retrospective group were not told. Caffeine reduced duration estimates in the prospective condition but not in the retrospective condition. The effect of caffeine on very long duration comparisons (the past year compared with a year at one-half and one-quarter of one's age) was also evaluated, but none was found. The findings do not support the hypothesis that caffeine affects duration experience by increasing the internal clock rate as a result of its dopamine D(2) agonist properties. The hypothesis that caffeine produces its effect by enhancing memory was considered and rejected. The most parsimonious explanation is that caffeine increased arousal level, which led to a narrowing of the focus of attention to the most salient task.

Adolescent↗