Individual difference in serial dependence results from opposite influences of perceptual choices and motor responses

Natural image statistics exhibit temporal regularities of slow changes and short-term correlations and visual perception, too, is biased towards recently seen stimuli, i.e., a positive serial dependence. Some studies report strong individual differences in serial dependence in perceptual decision making: some observers show positive serial effects, others repulsive effects, and some show no bias. To understand these contrasting results, this study separates the influences of physical stimuli per se, perceptual choices and motor responses on serial dependence in perceptual decision making. In two experiments, human observers reported which orientation (45° or −45°, at threshold contrast) they perceived. Experiment 1, used a consistent mapping between stimulus and response buttons while in Experiment 2, observers did two tasks: one with a consistent stimulus-response mapping, the other with a random stimulus-response mapping (perceptual choice and motor response unrelated). Results show that the stimulus percept (not the physical stimulus per se) affected subsequent perceptual choices in an attractive way, and that motor responses produced a repulsive serial effect. When the choice-response mapping was consistent (inseparable choice and response, typical of most experiments), individual differences in the overall serial effect was observed: some were positive, some repulsive, and some were bias-free. These individual differences likely reflect different relative weightings in individuals of a positive choice bias and a repulsive motor bias.

Trend Change Study of Climate Variables in Xin’anjiang-Fuchunjiang Watershed, China

This study emphasizes the precipitation and the maximum and minimum temperature trend and presents the results of study in temporal and spatial scales, after performing statistical analysis of the Xin’anjiang-Fuchunjiang watershed. Statistical Mann Kendall and Theil Sen techniques were used to determine the trend and its magnitude, respectively, and for determining the start and abrupt change in the trend, Sequential Mann Kendall test has been performed. Furthermore, statistical tests were performed to determine the overall trend in the area at a regional basis. For the removal of the serial effect of the data, prewhitening technique is applied. In this study, statistical tests were performed at 1901–2013 precipitation and temperature series and then after detection of the change year precipitation data were divided into two different scenarios of 1901–1960 period and 1961–2013 period. The results showed that precipitation trend is insignificant while maximum and minimum temperature have increased during 1901–2013 period except for some stations of autumn and summer seasons.

The serial effect on internal and external variables

ABSTRACTExamination of three variable concord phenomena in spoken Portuguese of Rio de Janeiro (noun phrase, subject/predicate adjective, subject/verb) demonstrates that the most consistent and strongest variable constraint on the use of concord is the discourse level serial (or parallel processing) effect, that is, a preference for similar forms to co-occur in sections of discourse, even if this results in redundancy or lack of economy. Given the strength of this constraint, we separated the data into two subsets such that one contains only serial occurrences, where parallel processing can operate, whereas the other contains only isolated or first occurrences, where there is no preceding form to trigger the parallel effect. In the serial set, the parallel effect is so strong that other nonsocial constraints are not selected. External forces, such as the normative pressure of the school system toward fully redundant marking, have no significant effect on the serial tokens, although education does correlate with increased use of concord in isolated/first tokens. Thus, in the serial context the linguistic system is so highly constrained that external, and even internal, influences are blocked. We conclude that strong constraints should be identified, and that data in which they are operative should be analyzed separately from data in which they are not present in order to understand the interplay of the diverse forces in the linguistic system.