Colored-Speech Synaesthesia Is Triggered by Multisensory, Not Unisensory, Perception

ABSTRACT— Although it is estimated that as many as 4% of people experience some form of enhanced cross talk between (or within) the senses, known as synaesthesia, very little is understood about the level of information processing required to induce a synaesthetic experience. In work presented here, we used a well-known multisensory illusion called the McGurk effect to show that synaesthesia is driven by late, perceptual processing, rather than early, unisensory processing. Specifically, we tested 9 linguistic-color synaesthetes and found that the colors induced by spoken words are related to what is perceived (i.e., the illusory combination of audio and visual inputs) and not to the auditory component alone. Our findings indicate that color-speech synaesthesia is triggered only when a significant amount of information processing has occurred and that early sensory activation is not directly linked to the synaesthetic experience.     

Theoretical approximations of stuttering adaptation: Statement of predictive accuracy

An empirical and theoretical discussion is presented with reference to the validity and interpretation of a predictive table of stuttering adaptation. A comparison of actual data with predicted data indicated that the predictive table of stuttering adaptation was highly accurate. The implications of the theoretical model for the predictive table are discussed in terms of current day interpretations of research data in stuttering adaptation.     

Do monocular time-to-collision estimates necessarily involve perceived distance?

Motivated by the debate between indirect and direct theories of perception, a large number of researchers have attempted to determine whether judgments of time to collision are based on the ratio of perceived distance to perceived speed or on the ratio theta/(d theta/dt), i.e. tau. Despite the considerable research effort devoted to this question there seems to be no clear resolution. We used a staircase tracking procedure to estimate errors in estimating time to collision for a simulated approaching object. To investigate the role of perceived distance in the judgment of time to collision, we asked observers to alternate between two viewing distances (100 and 500 cm). For the 500 cm viewing distance, we magnified the visual display by a factor of five so that the retinal images [and the values of theta/(d theta/dt) through time] were identical for the two viewing distances. All visual cues to distance were available. There were no significant differences between estimates of time to collision made at the two viewing distances. We conclude that our observers ignored perceived distance when estimating time to collision and based their responses on theta/(d theta/dt). We concur with recent proposals that, in the future, time-to-collision research should move away from the either/or analysis of different information sources that has dominated previous studies towards investigations of how different information sources are integrated.     

Subjective phrase structure: An empirical investigation

The present study represents an attempt to investigate the basis of subjective groupings of words in sentences, employing Edwin Martin's subjective phrase structure technique. Results indicate that subjects base their judgments not only on grammatical structure but also on constituent length and on stress and intonation patterns.A shorter version of this paper was presented to the Annual Meeting of the Canadian Linguistic Association at McGill University, Montreal, May 1972.     

Book reviews

DIAMOND, S. J. The Social Behaviour of Animals. London: Baqtsford. 1970. Pp. 256. £2.50.

JARRARD, L. E. (Ed.). Cognitive Processes in Non-human Primates. New York: Academic Press. 1971. Pp. 188.

BROZEK, J. and SLOBIN, D. I. (Eds). Psychology in the USSER: An Historical Perspective. New York: International Arts and Sciences Press. 1972. Pp. x + 30.1. $ 15.00.

A. R. JENSEN. Genetics and Education. London: Methuen. 1972. Pp. Vii + 379. £ 3.50.

OATLEY, K. Brain Mechanisms and Mind. London: Thames and Husdson. 1972. Pp. 216. £2.25.

BOAKES, R. A. and HALLIDAY, M. S., (Eds). Inhibition and Learning. London: Academic Press 1972. Pp. 568. £7.25.

TOBACH, E., ARONSON, L. R. and SHAW, E. (Eds). The Biopsychology of Development. New York: Academic Press. 1971. Pp.xix + 593. dollar 22.50.

MOLTZ, H. (Ed.). The Ontogeny of Vertebrate Behavior. New York and London: Academic Press. 1971. Pp. 500. $ 22.50.

SOKOLOV, A. N. Inner Speech and Thought. London: Plenum Publishment Co. 1972. Pp. 283. £ 10.50

SHOUKSMITH, G. Intelligence, Creativity and Cognivity and Cognitive Style. LOndon: Batsford. 1970.Pp. 240. £ 2.30,

BOLTON, N. The psychology of Thinking. Lond Methuuen. 1972. Pp. 291. £3.20.

JOHNSON, D. M. Systematic Introduction to The Psychology of Thinking. New York: Harper and Row, 1972. Pp. 498. £ 5.10.

LLOYD, B. Preception and Cognition. Harmondsworth: Penguin Books. 1972. Pp. 190. £ 0.80.     

Forgetting as a function of sleep at different times of day

The experiment studied the separate effects of sleep and time period of retention interval on forgetting. A free recall task was given to independent groups of subjects either at night or in the morning, and a second recall demanded 5 h later, after an intervening period of sleeping or waking activity. Oral body temperatures (BT) were measured at each session. The data were analysed in terms of (a) immediate recall at test 1, and (b) amount forgotten from test 1 to test 2. Immediate recall was higher for morning groups, in agreement with previous findings, serial position analysis indicating that the effect is confined to enhancement of the primary memory component. Long-term retention was higher over the night interval, irrespective of sleeping conditions, though having slept at night produced better retention than having stayed awake. Sleep during the morning was not effective in reducing forgetting. BT showed a marked drop for both night groups and rise for day groups over the retention interval. Alternative explanations for the classical sleep/memory findings are suggested in terms of (a) differential effects of sleep stages on memory, and (b) the underlying diurnal variation in BT and other processes.