Academic journal article Canadian Journal of Experimental Psychology

The Effect of Spatial Attention on Memory Scanning

Academic journal article Canadian Journal of Experimental Psychology

The Effect of Spatial Attention on Memory Scanning

Article excerpt

Abstract Participants responded to probe letters after sets of two, four, and six letters were memorized (Sternberg, 1966, 1969b). Spatial attention was controlled by central arrow cues and stimuli were presented in a clear or a visually degraded form. Overall RT was shorter for attended than for unattended locations, and shorter for clear than for degraded stimuli. Even though the function relating RT to memory-set size for stimuli in attended locations had a significantly smaller zero-intercept than the function for unattended locations, the slope was unchanged, which suggests that attention did not influence the memory-scanning stage. Visual quality interacted with attention, which suggests that they influenced the same stage of processing, presumably the early visual-encoding stage of processing.

Spatial attention is an important component of visual cognition. Posner (1980) and his colleagues (e.g., Posner, Snyder, & Davidson, 1980) have developed a technique for manipulating spatial attention independently of eye movements. In a typical spatial cuing experiment, the main task of the subject is to press a key when a target appears in visual space. Before the target appears, a cue is presented, which provides information about the location of the target. Typically, a peripheral cue consists of a peripheral flash or brightening that indicates the likely location of the stimulus. A central cue consists of a centrally displayed arrow that points to the likely location of the stimulus. The cues are provided so that subjects can focus their attention on the cued location before the appearance of the stimulus. In the majority of trials, the cue would be valid (i.e., the target appears in the location indicated) and on the remaining trials it is invalid (the target appears in another location).

Studies using this procedure have shown that the detection of stimuli is more efficient at cued locations than at uncued locations (Eriksen & Hoffman, 1972, 1973; Posner, 1980; Jonides, 1980, 1981; Posner, Snyder, & Davidson, 1980). Clear benefits can be shown for valid cues: Performance is faster and/or more accurate following valid cues than neutral cues. Costs can be shown for invalid cues: Performance is slower and/or less accurate following invalid cues than neutral cues. These benefits and costs from the cue occur even when subjects do not move their eyes to the cued location (e.g. Posner, Nissen, & Ogden, 1978).

Most of the spatial cuing experiments have been concerned with the effect of directing attention on the detection of stimuli. Little has been done on the influence of visual attention on higher-level cognitive tasks, i.e., where a response would involve making a decision between two or more alternatives. In responding to a higher-level cognitive task, detecting the stimulus may only be the first stage or process in a series of mental processes involved in the response. Directing attention to the location of the stimulus might result in faster detection of the stimulus, but how would it affect subsequent processes or stages? Only a few studies investigating this issue have been reported (e.g., Corballis & Manalo, 1993; McCann, Folk, &Johnston,1992).

Corballis and Manalo (1993) investigated the influence of attention on a higher-level cognitive task: mental rotation. In their experiment, the letter R was presented in varying angular orientations in the left or right visual field and subjects had to decide whether the letter was normal or mirror reversed. This task has been shown to induce subjects to mentally rotate the letter to the upright before making the decision (Cooper & Shepard, 1973). Before the appearance of the letter, a centrally located arrow indicated the likely side that the letter would appear on. Subjects fixated centrally and the letters were presented 6 from fixation. It is well known that visual acuity drops off quite sharply from fixation, but this can be offset by using larger stimuli. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.