Pause measures during reading and recall in serial list learning

An investigation is reported into pausing and grouping during the serial learning of letter strings, when presented randomly by length and when presented in ascending order. Mean pause times for the reading and recall of longer lists were significantly greater than for lists of shorter span due to extended pausing at specific list positions. In general, reading rhythms were duplicated during recall. Subjects were highly consistent in maintaining their level of pause duration across lists and responded to additions in list length by increasing their number of groups, not by increasing group size. Triadic sequences were the most popular form of spontaneous organization. Pausing measures are discussed as indices of organizational strategies.     

A circuit to permit an electronic drinkometer to operate during footshock

A circuit to permit an electronic drinkometer to operate during footshock is described. The circuit employs a diode matrix that allows all grid bars to be connected at one point to form one electrode of the drinkometer; it is isolated at another point so as not to shortcircuit the impressed footshock.     

“Center-of-gravity” Tendencies for fixations and flow patterns

Fixation positions were measured for a variety of simple patterns. Generally, the spontaneous fixation tendencies hovered near the “center-of-gravity” of the pattern, providing that the overall dimensions of the figure were less than about 5 deg. “Open” figures such as angles were found to be roughly equivalent to their “enclosed” counterparts, such as triangles. The constraints imposed by the pattern upon the fixation tendencies occur at a level where the binocular inputs are processed. Of further importance was the fact that the fixation points approximate the foci observed in the same patterns when they are seen against a background of visual noise. It is suggested that the two results may be functionally related..     

Stereopsis with opposite contrast contours

The effects of incidental stimuli, defined as visual stimuli not under verbal control, upon a selection task were observed as a function of feedback contingency. Ss judged letter pairs to be valid or invalid completions of preceding letter parts. During the presentation of the letter parts, the response pair or an alternative pair of letters was intermittently presented at a threshold value individually determined for each S. One group of Ss received a light feedback of performance contingent upon responding to the incidental stimuli; whereas a second group received a random noncontingent feedback. The results indicated: (a) both groups responded to the incidental stimuli; (b) feedback contingency had no effect on frequency of responding to the incidental stimuli; (c) frequency of responding to the incidental stimuli remained constant over 32 trials.     

Continuity effects with alternately sounding tones under dichotic presentation

An experiment is reported in which 10 Ss possessing normal hearing were required to make discriminations of continuity or interruption in a longer less intense signal (Tone A) which alternated in time with a shorter more intense signal (Tone B). The signals were presented dichotically with Tone A at the right ear. Three Tone B frequencies of 300, 1000, and 4000 cps and five Tone A frequencies somewhat near each of the Tone B frequencies were employed. The results demonstrated that as Tone A was nearer to Tone B in frequency, continuity thresholds in Tone A occurred at longer durations of Tone B. The results are discussed in terms of a central neural model.     

Prototyping “Intelligent” applications for interactive multimedia systems

The termmultimedia refers to the combined use of different media of communication, and originally belonged primarily to the fields of entertainment and education. Advances in computer, audio, and video technology have now brought multimedia possibilities to the individual. Further, they give the user control over what happens. Suchinteractive multimedia systems offer the user personal access to large amounts of information, including pictures, graphics, video, text, and audio. The potential range of applications is very broad, from simple interactions where the user will merely make occasional choices and then sit back and view sections of program material, to more purposeful interactions where the application can help the user to achieve a goal. This article describes research onknowledge-based interactive multimedia systems. Targeted on the new Compact Disc Interactive format, we have protyped an advisor which will help the user to tackle a typical domestic task. The necessary decision-making process can be enlivened by multimedia interaction, and placed on solid ground by the inclusion of expert advice.     

Asymmetries in the regulation of visually guided aiming

An experiment was conducted to examine the contribution of sensory information to asymmetries in manual aiming. Movements were performed in four vision conditions. In the full-vision condition (FV), subjects were afforded vision of both the hand and the target throughout the course of the movement. In the ambient-illumination-off condition (AO), the room lights were extinguished at movement initiation, preventing vision of the moving limb. In the target-off (TO) condition, the target was extinguished upon initiation of the movement. In a no-vision (NV) condition, ambient illumination was removed and the target was extinguished upon initiation of the response movement. Results indicated that accuracy was superior in the full-vision and target-off conditions and when movements were made by the right hand. Movements made by the right hand were also of shorter mean duration. The magnitudes of performance asymmetries were uninfluenced by vision condition. Analyses of movement kinematics revealed that movements made in conditions in which there was vision of the limb exhibited a greater number of discrete modifications of the movement trajectory. On an individual-trial basis, no relationship existed between accuracy and the occurrence of discrete modifications. These data suggest that although vision greatly enhances accuracy, discrete modifications subserved by vision reflect the imposition of nonfunctional zero-order control processes upon continuous higher-order control regimes.