Daniel Holender

Semantic activation without conscious identification in dichotic listening, parafoveal vision, and visual masking: A survey and appraisal

When the stored representation of the meaning of a stimulus is accessed through the processing of a sensory input it is maintained in an activated state for a certain amount of time that allows for further processing. This semantic activation is generally accompanied by conscious identification, which can be demonstrated by the ability of a person to perform discriminations on the basis of the meaning of the stimulus. The idea that a sensory input can give rise to semantic activation without concomitant conscious identification was the central thesis of the controversial research in subliminal perception. Recently, new claims for the existence of such phenomena have arisen from studies in dichotic listening, parafoveal vision, and visual pattern masking. Because of the fundamental role played by these types of experiments in cognitive psychology, the new assertions have raised widespread interest. The purpose of this paper is to show that this enthusiasm may be premature. Analysis of the three new lines of evidence for semantic activation without conscious identification leads to the following conclusions. (1) Dichotic listening cannot provide the conditions needed to demonstrate the phenomenon. These conditions are better fulfilled in parafoveal vision and are realized ideally in pattern masking. (2) Evidence for the phenomenon is very scanty for parafoveal vision, but several tentative demonstrations have been reported for pattern masking. It can be shown, however, that none of these studies has included the requisite controls to ensure that semantic activation was not accompanied by conscious identification of the stimulus at the time of presentation. (3) On the basis of current evidence it is most likely that these stimuli were indeed consciously identified.

Unconscious perception: the need for a paradigm shift.

According to Snodgrass, Bernat, and Shevrin (2004), unconscious perception can be demonstrated convincingly only at the objective detection threshold, provided that the conditions of theirobjective detection/strategic model are met, whereas both thesubjective threshold model of Cheesman and Merikle (1984, 1986) and theobjective threshold/rapid decay model of Greenwald, Draine, and Abrams (1996) are inconclusive. We argue on theoretical, metatheoretical, and empirical grounds that all three dual-process models, which are based on both conscious and unconscious perception, should be rejected in favor of thesingle-process conscious perception model.

Selective preparation and time uncertainty.

Discrete two-choice reaction time experiments were performed under two time-uncertainty conditions provided by constant foreperiods of either 5.0 or 0.5 sec. The problem was how to know whether selective preparation may be maintained over time or whether it is a short-term process. Selective preparation of one of the two stimuli was induced through monetary incentive in Experiment 1 and through frequency unbalance in Experiment 4, it was assessed through prediction in Experiments 3 and 4. With all three manipulations the effects of selective preparation and of time uncertainty were found to combine additively. Those results support the idea that selective preparation can be maintained over time. On the other hand, the improvement in reaction time due to a reduction of time uncertainty is achieved by a short-term preparatory adjustment which is not stimulus-specific.

No negative semantic priming from unconscious flanker words in sight.

In replicating 1 of the within-language conditions of E. Foxs (1996) Experiment 1, the authors confirmed that unattended words presented 2.4 degrees above and below fixation are mostly unavailable to awareness. However, no negative semantic priming was observed in a lexical decision on a probe letter string appearing about 1 s later, which does not replicate Foxs finding. These results are compatible with the hypothesis underlying the present study, according to which positive semantic priming, if any, rather than negative semantic priming is expected in Foxs situation. The reason is that unavailability to awareness of the parafoveal words is not achieved by means of an act of selective inhibition combined with attentional diversion through masking but is achieved simply by means of perceptual degradation.

Revisiting the affective Simon effect

We replicated the affective Simon effect found by De Houwer and Eelen (1998) in a situation in which participants had to respond by saying positive or negative depending on the grammatical category of the stimulus words while ignoring their affective connotation. Our results show that the affective Simon effect can be modulated by varying the proportion of experimental stimuli bearing a strongly polarised affective connotation. We propose that affective Simon effect depends at least in part on participants’ awareness of the correspondence between the affective connotation of the words and the responses. We also submit that this effect might not be specific to affective processing in that it is a token of a vast category of congruity effects that can be based on any kind of meaning of the stimuli, whether semantic or affective.

Identification of letters in words and of single letters with pre- and postknowledge vs. postknowledge of the alternatives

Two experiments were conducted to test how the “word letter phenomenon” (WLP)—a letter is better identified when embedded in a word than when presented alone—is affected by prior knowledge of the alternatives in a forced choice paradigm with tachistoscopic exposures. In Experiment 1, one group of subjects, who were given knowledge of the alternatives after the display, showed the usual WLP. The WLP was eliminated in a second group of subjects who were given knowledge of the alternatives both before and after the display. In Experiment 2, the same subjects were either precued or not precued on alternating trials of each block. It appeared that the WLP suppression with precuing resulted from a decrease in word performance whereas letter performance was unaffected by precuing. It is suggested that precuing exerts a detrimental effect, because, instead of attending to the word as a whole, subjects search for where in the word the forced choice would be plausible.

Visual-field differences for a number--non-number classification of alphabetic and ideographic stimuli

Subjects made a number-non-number classification for single numbers or non-numbers presented either in the left or right visual field. A right visual field advantage was observed both for numbers written ideographically (Arabic numerals) and alphabetically. The laterality effect was stronger for the alphabetic than for the ideographic script, but the interaction with visual field failed to reach statistical significance. The results are discussed in the framework of other studies contrasting the processing of logographic and phonographic scripts as a function of the visual field.

The Role of Decision Biases in Semantic Priming Effects

At least a part of semantic priming effects observed in binary decision tasks is supposed to be caused by decision biases. A semantic relationship between prime and target could positively bias a “yes” response, whereas the absence of a relationship would instead favour a “no” response to the same target. We tested this assumption with a semantic categorization task in which participants were induced to associate different values - positive, negative, or neutral - to each of the categorization decisions. Although semantic priming effects were obtained even with negatively valued decisions, they were substantially enhanced with positively valued decisions, confirming the influence of a decision bias induced presumptively by a post-lexical relatedness judgement.

Unconscious semantic access: A case against a hyperpowerful unconscious

We analyze some of the recent evidence for unconscious semantic access stemming from tasks that, although based on a priming procedure, generate semantic congruity effects because of response competition, not semantic priming effects. We argue that such effects cannot occur without at least some glimpses of awareness about the identity and the meaning of a significant proportion of the primes.

SYNCHRONIC DESCRIPTION OF PRESENT-DAY WRITING SYSTEMS: SOME IMPLICATIONS FOR READING RESEARCH

First, the characteristics of present-day writing systems are illustrated by describing how Chinese, Japanese, Korean, Hebrew, Arabic, and Hindi are conveyed by script. This is followed by a discussion about the nature of the linguistic units that are, or that should be represented by alphabetic scripts. The last part of this chapter is a brief description of the different lines of research bearing on how the reading processes are modulated by the properties of the writing systems.