Unconscious forces: a survey of some concepts in Indian philosophy

In this article, I examine some traditional Indian conceptions of unconscious mental activity. There are concepts in the Indian philosophical tradition, notably saskāras and vāsanās, which can be taken to refer to unconscious mental states and dispositions. My discussion, which is essentially philosophical by nature, is loosely based on the English philosopher C.D. Broad's distinctions concerning the unconscious. Saskāras, which are interpreted realistically in Indian tradition, may manifest themselves as what I (and Broad) call relatively unconscious states. Evidence for this interpretation can be found in discussions concerning the nature of dream state and the supernatural powers of yogis in Indian tradition. It is interesting to try to view the retributive system of karma as an absolutely unconscious system, but this is not a plausible interpretation of the Indian view of karma.     

How many faces can be processed during a single eye fixation?

The purpose of our study was to estimate the perceptual span for facial information: how many faces can be processed during a single eye fixation. We used a visual-search task, in which the targets and distractors were facial photographs. The task of the observer was to search for and identify a target face in an array of faces. We measured the time needed for one search--threshold search time--by using a multiple-alternative staircase method. The threshold represents the duration of stimulus presentation at which the probability of correct responses was 79%. The array size was varied from 2 x 2 to 8 x 8 faces. Simultaneously with the performance measurements we measured eye movements with a video eye tracker. We found that threshold search time increased with increasing set size nearly linearly. The number of fixations also increased linearly from unity at the smallest set size to about fifteen at the largest set size. The result of 2 x 2 faces during a single fixation gave an estimate of 4 faces for the perceptual span. If, on average, only half of the elements had to be scanned for finding the target, 15 fixations at the largest set size (8 x 8) gave another estimate of 2.13 faces. The mean fixation duration was around 200 ms. Thus, the results suggest that 2-4 faces can be processed during one fixation of about 200 ms.     

Mental relaxation improves long-term incidental visual memory

Experimental evidence has linked increased arousal to enhanced memory retention. There is also evidence that procedures reducing arousal, i.e., mental relaxation, might improve memory, but conflicting results have been reported. To clarify this issue, we studied the effects of a single session of relaxation training on incidental visual long-term memory. Thirty-two relaxation-naive subjects viewed 280 slides without being told that there would be subsequent memory testing. Afterwards, subjects listened to a 12 min relaxation tape; 16 subjects relaxed by following the instructions (relaxation group), and the other 16 subjects pressed a button whenever a body part was mentioned (control group). While listening to the relaxation tape, high frequency heart rate variability (HRV) was greater and low frequency HRV was lower in the relaxation group, implying effective relaxation and increasing parasympathetic activation. The relaxation group had superior memory retention 4 weeks later (p = .004), indicating enhancement of long-term memory performance. This effect could not be explained by retroactive interference experienced in the control group because short-term memory performance immediately after the tape was slightly better in the control group. Retention of materials acquired after the relaxation session remained unaffected, suggesting relaxation has retrograde effects on memory consolidation. Our data demonstrate a favorable influence of relaxation on at least this aspect of learning. Our data also extend previous knowledge on the beneficial effects of ascending parasympathetic stimulation on memory retention in that enhanced long-term memory consolidation may also occur in the presence of central and descending parasympathetic activation triggered by willful psychomotor activity.     

Determinants of picture naming times in Icelandic

Numerous studies have found that word frequency has a significant effect on the time it takes to name an object or read a word. Recently, claims have been made that this frequency effect is perhaps more correctly interpreted as an age of acquisition effect. This paper reports an experiment in which naming times in Icelandic for 175 stimuli from the Snodgrass and Vanderwart picture set were determined. A multiple regression analysis of naming times against a number of independent factors showed that objective age of acquisition was the strongest predictor of naming time, with familiarity and name agreement also showing a significant effect. The effect of word frequency was, however, not significant. Possible reasons for this are discussed.     

Does mood influence the realism of confidence judgments?

Previous research has shown that mood affects cognition, but the extent to which mood affects meta-cognitive judgments is a relatively over-looked issue. In the current study we investigated how mood influences the degree of realism in participants' confidence judgments (based on an episodic memory task). Using music and film in combination, we successfully induced an elated mood in half of the participants, but failed to induce a sad mood in the other half. In line with previous research, the participants in both conditions were overconfident in their judgments. However, and contrary to our prediction, our data indicated that there was no difference in the realism of the confidence between the conditions. When relating this result to previous research, our conclusion is that there is no, or very little, influence of mood of moderate intensity on the realism of confidence judgments.     

Effects of displayed emotion on attitude and impression formation in visual speech-reading

In two experiments on visual speech-reading, with a total of 132 normal-hearing participants, the effects of displayed emotion and task specificity on speech-reading performance, on attitude toward the task and on person impression were explored, as well as associations between speech-reading performance, attitude, and person impression. The results show that displayed emotion increased speech-reading performance and attitude ratings, and that the actor was perceived as more extraverted both when displaying emotions, and when his speech was high in specificity The main conclusion was that displayed emotion enhances speech-reading performance by providing information that is useful to the speech-reader.     

The auditory sensory memory trace decays rapidly in newborns

The present study investigated the temporal dynamics of auditory sensory memory in newborns as reflected by the mismatch negativity (MMN), a preattentive electric change-detection response. MMN was obtained from 24 full-term healthy newborns who were either awake or asleep (quiet or active sleep) during the experiments. Stimuli were 1,000 Hz tones (standards) that were occasionally replaced by 1,100 Hz tones (deviants). The constant stimulus onset asynchrony (SOA) was, in separate blocks, either 450, 800, or 1,500 ms. A prominent MMN was obtained at the 800 ms SOA in all three sleep or waking states, whereas no MMN occurred at 450 and 1,500 ms SOAs. In view of the fact that in adults MMN is elicited even with a 10s SOA, these results imply that the time span of auditory memory is considerably shorter in neonates than in adults and 8-12-year-old children.     

Flank transparency: the effects of gaps,line spacing,and apparent motion

We analyze the properties of a dynamic color-spreading display created by adding narrow colored flanks to rigidly moving black lines where these lines fall in the interior of a stationary virtual disk. This recently introduced display (Wollschl?ger et al, 2001 Perception 30 1423-1426) induces the perception of a colored transparent disk bounded by strong illusory contours. It provides a link between the classical neon-color-spreading effect and edge-induced color spreading as discussed by Pinna et al (2001 Vision Research 41 2669-2676). We performed three experiments to quantitatively study (i) the enhancing influence of apparent motion; (ii) the degrading effect of small spatial discontinuities (gaps) between lines and flanks; and (iii) the spatial extent of the color spreading. We interpret the results as due to varying degrees of objecthood of the dynamically specified disk: increased objecthood leads to increased surface visibility in both contour and color.     

Prognostic indicators for stuttering: the value of computer-based speech analysis

There are currently no known acoustic parameters by which stuttering children can be appraised in order to predict the further course of their speech disfluency. The present study investigates the usefulness of a computer-based speech analysis of fluent utterances. Correlations between acoustic variables, severity, and course of stuttering were sought in a prospective longitudinal study. This analyzed 57 preschool children at 6-month intervals over a period of 4.6 years. The acoustic analyses yielded no clearly distinguishing characteristics. There was, however, one subgroup consisting of children who were still disfluent at study end which showed more variable values at various measurement points for different parameters. Speech control seems to be different in children exhibiting chronic stuttering.     

Neuromagnetic evidence for the timing of lexical activation: an MEG component sensitive to phonotactic probability but not to neighborhood density

Evidence from electrophysiological measures such as ERPs (event-related potentials) and MEG (magnetoencephalography) suggest that the first evoked brain response component sensitive to stimulus properties affecting reaction times in word recognition tasks occurs at 300-400 ms. The present study used the stimulus manipulation of Vitevich and Luce (1999) to investigate whether the M350, an MEG response component peaking at 300-400 ms, reflects lexical or postlexical processing. Stimuli were simultaneously varied in phonotactic probability, which facilitates lexical activation, and in phonological neighborhood density, which inhibits the lexical decision process. The present results indicate that the M350 shows facilitation by phonotactic probability rather than inhibition by neighborhood density. Thus the M350 cannot be a postlexical component.