Size matters: saccades during scene perception

We investigated the effect of image size on saccade amplitudes. First, in a meta-analysis, relevant results from previous scene perception studies are summarised, suggesting the possibility of a linear relationship between mean saccade amplitude and image size. Forty-eight observers viewed 96 colour scene images scaled to four different sizes, while their eye movements were recorded. Mean and median saccade amplitudes were found to be directly proportional to image size, while the mode of the distribution lay in the range of very short saccades. However, saccade amplitudes expressed as percentages of image size were not constant over the different image sizes; on smaller stimulus images, the relative saccades were found to be larger, and vice versa. In sum, and as far as mean and median saccade amplitudes are concerned, the size of stimulus images is the dominant factor. Other factors, such as image properties, viewing task, or measurement equipment, are only of subordinate importance. Thus, the role of stimulus size has to be reconsidered, in theoretical as well as methodological terms.     

Utilization of covariation knowledge in source monitoring: no evidence for implicit processes

In three experiments, a "hidden covariation" (Lewicki, in Journal of Experimental Psychology: Learning, Memory, and Cognition, 12, 135-146, 1986) of nonsalient stimulus attributes and the source of stimulus information was established to test whether implicit knowledge about this correlation influences source memory judgments. The source monitoring framework (Johnson, Hashtroudi, and Lindsay, in Psychological Bulletin, 114, 3-28, 1993) postulates heuristic and strategic judgment processes in source attributions. A multinomial model analysis disentangled memory and guessing processes. While there were large strategic guessing biases involving explicit knowledge in all experiments, there was no evidence for the use of implicit covariation knowledge. Only participants who were later able to verbalize the covariation had shown corresponding biases during the source memory test, suggesting that implicit covariation knowledge plays no prominent role in the reconstruction processes in source monitoring.     

History of experimental psychology from an Estonian perspective

A short review of the development of experimental psychology from an Estonian perspective is presented. The first rector after the reopening of the University of Dorpat (Tartu) in 1802, Georg Friedrich Parrot (1767–1852) was interested in optical phenomena which he attempted to explain by introducing the concept of unconscious inferences, anticipating a similar theory proposed by Herman von Helmholtz 20 years later. One of the next rectors, Alfred Wilhelm Volkmann (1800–1878) was regarded by Edwin Boring as one of the founding fathers of the experimental psychology. Georg Wilhelm Struve (1793–1864) played an essential part in solving the problem of personal equations. Arthur Joachim von Oettingen (1836–1920) developed a theory of music harmony, which stimulated his student Wilhelm Friedrich Ostwald (1853–1932) to study colour harmony. Emil Kraepelin (1856–1926), the founder of modern psychiatry, is by far the most important experimental psychologist who has worked in Estonia. His successor Wladimir von Tchisch (1855–1922), another student of Wilhelm Wundt, continued Kraepelin’s work in experimental psychology. The lives of Wolfgang Köhler (1887–1967), who was born in Reval (Tallinn), and Oswald Külpe (1862–1915), who graduated from the University of Dorpat, extended the link between the history of experimental psychology and Estonia. Karl Gustav Girgensohn (1875–1925), the founder of the Dorpat School of the psychology of religion, stretched the use of experimental methods to the study of religious experience.