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Biomedical subjects

R H Phaf

Publications and source records attributed to R H Phaf.

7 recordsLinked to original sources
PubMed2001

Stronger suboptimal than optimal affective priming?

The finding of stronger affective priming in less conscious (suboptimal) conditions than in fully conscious (optimal) conditions (S. T. Murphy & R. B. Zajonc, 1993) is theoretically important because it contradicts notions that emotions are primarily reflected by conscious states. In 2 experiments, this pattern of results was obtained. Happy and angry faces were presented both optimally and suboptimally and were masked by unknown ideographs. In Experiment 1, instructions for the conscious and less conscious affective priming conditions were matched, and affective ratings of ideographs were determined. In Experiment 2, a more implicit affective measure (facial electromyography of musculus zygomaticus major and musculus corrugator supercilii) served as the dependent variable. Stronger suboptimal than optimal affective priming was found in both experiments. It is concluded that stronger suboptimal than optimal processing is characteristic for affective processing and that it can also be found when instructions are matched and when a more implicit measure is assessed.

Adolescent↗
PubMed1998

Connectionist investigations of individual differences in Stroop performance.

A simple connectionist model for the Stroop task was implemented to investigate a defective inhibition hypothesis first postulated by Fox in 1994 for individuals of high anxiety. Simulations with this model indicated that Stroop interference was positively, instead of negatively, related to inhibition. An alternative excitation hypothesis assuming that high anxiety corresponds to stronger verbal connections to the distracting material could also be investigated in the model. Stronger verbal connections indeed corresponded to larger interference. It is argued that this type of simulation could be useful, not because it proves in any way the supposed mechanisms, but because it clarifies the relation between theory and empirical data and so stimulates further specification of theoretical assumptions and invites empirical research into these assumptions.

Anxiety↗
PubMed1997

Asymmetric affective evaluation of words and faces.

In two experiments the relationship between direct and indirect forms of affective evaluation was investigated within the framework of a dual-pathway model (LeDoux, 1986, 1989). Emotionally valenced faces were hypothesized to be more directly evaluated affectively than valenced words. A Stroop-like asymmetry was expected, with faces interfering more with word evaluation than vice versa. Similar to experiments investigating affective influences of words on words (Greenwald, Klinger & Liu, 1989), a backward dichoptic pattern-masking technique was used in both experiments, with lateralized presentations of targets and masked primes in a short and a long presentation condition. In Expt 1, priming of emotionally negative, neutral and positive faces on the affective evaluation of emotionally negative, neutral and positive words was investigated in a two-alternative forced-choice task. In Expt 2, primes and targets were reversed. A clear asymmetry occurred in both subliminal and supraliminal conditions, but completely opposite to the one expected. Implications for a dual-pathway model are discussed.

Affect↗
PubMed1996

Processing familiar and unfamiliar auditory stimuli during general anesthesia.

We tested memory priming for auditory stimuli presented during general propofol-sufentanil anesthesia in 58 patients undergoing day-case arthroscopic surgery. Stimuli were presented via headphones and consisted of common facts (Group A, 29 patients), or familiar or unfamiliar full names of fictitious people (GRoup B, 29 patients). Group A was expected to give more correct answers to questions about the common facts than Group B, when tested postoperatively, and Group B to attribute more fame to presented names than Group A (famous names test). Because the process for learning new or unfamiliar stimuli (elaboration) in particular may be impaired under general anesthesia, more memory priming was expected for familiar than for unfamiliar material. No significant differences were demonstrated between the two groups in performance on common facts or in fame attributed to the names. The amount of memory priming, however, was positively related to one of two measures of preoperative anxiety.

Acoustic Stimulation↗
PubMed1990

SLAM: a connectionist model for attention in visual selection tasks.

SLAM, the SeLective Attention Model, performs visual selective attention tasks, an analysis of which shows that two processes, object and attribute selection, are both necessary and sufficient. It is based upon the McClelland and Rumelhart (1981) model for visual word recognition, with the addition of a response selection and evaluation mechanism. The responses may be correct or incorrect and, in particular conditions, SLAM may not make a response at all. Moreover, it allows for the generation of specific responses in time. SLAM's main characteristics are parallelism restricted by competition within modules, heterarchical processing in a hierarchical structure, and generation of responses as a result of relaxation given the conjoint constraints of stimulation, object, and attribute selection. The model is considered to represent an individual subject performing filtering tasks and demonstrates appropriate selective behavior. It is also tested quantitatively using a single tentative set of model parameters. The study reports simulations of four different filtering experiments, modeling response latencies, and error proportions. Specifications are made to take account of instructions, previous trials, and the effect of a barmarker cue and of asynchronies in stimulus and cue onsets. The model is then extended in order to provide simulations of a number of Stroop experiments, which can be regarded as filtering tasks with nonequivalent stimuli. The extension required for Stroop simulations is the addition of direct connections between compatible stimulus and response aspects. The direct connections do not affect the simulation of simpler filtering tasks. A variety of different experiments carried out by different authors is simulated. The model is discussed in terms of how modular architecture and the interaction of excitation and inhibition generate facilitation or inhibition of response latencies.

Arousal↗