Rapid serial visual presentation

Rapid serial visual presentation is an experimental model frequently used to examine the temporal characteristics of attention. The RSVP paradigm entails participants to look at a continuous presentation of visual items which is around 10 items per second. They are all shown in the same place. The targets are implanted inside this stream of continuous items. They are separate from the rest of the items and can be called distracters. The distracters can either be a color change or it can be letters that are among the numbers.

Overview

There is a delay of several hundred milliseconds. For example, a person might be asked to identify numbers in a string of letters which are shown one by one. The first number which is an important target, would be caught by the person, however, the second number flashed seconds later might not be observed. There are a number of theories to explain how and why this works and studies have explored its limitations and parameters to learn more about visual perception. The brain deals with a quick stream of incoming information at all times. With the attentional blink, the brain has to distribute its attentional resources to comprehend, interpret, and store the information properly. The human brain is able of processing complex tasks, but it has restrictions. The attentional blink is an illustration that has a significant insinuation for individuals who work in environments where they are usually swamped with information. An example of this is an airport baggage screener who might see a knife in one bag, but misses a second knife in another bag that is right behind the first bag. The failure to recognize the second target is because of the attentional processes that are linked with the identification of the first target.

History

Potter (1976) ^[1] explored the amount people are able to comprehend and memorize information from fast series of stimuli. Potter had participants search for the RSVP series of pictures for a specific picture which was the target. This was depicted before the appearance of the RSVP series. Results showed that participants performed well on this task. Here, the RSVP rate was eight items per second; however, participants were still able to accurately find the target on 75% of the trials. Performance was not different in the pictures that were previously presented or described. Each picture was acknowledged within 125 milliseconds. However, Potter & Levy (1969) found that performance did change when participants were assessed on a recognition task for the pictures presented in the RSVP sequence. The results showed that the participants’ performance accurately scored 10% in the task when the RSVP rate was eight items per second.

Sperling and colleagues examined the RSVP paradigm to investigate the dynamics of shifts of spatial attention (e.g., Reeves & Sperling, 1986; Sperling & Weichselgartner, 1995).^[2][3] Spatial attention is defined as the ability to center on specific stimuli in a visual environment (Johnson & Proctor, 2004). Sperling used an attention shift procedure in which two RSVP series were presented altogether. There was a central point where one was to the left and the other was to the right of the focus point. One series contained letters and the other series contained numbers. The object of the task was for participants to focus on the letter stream and to report items from the number series following a certain letter. Results showed that participants frequently reported numbers that were heard around 400 milliseconds after the cue. They concluded that the findings were parallel with the time participants were required to shift attention from the series that had the letters to the series that had the numbers.

Weichselgartner and Sperling (1987)^[4] examined if the same conclusions would be made if the participants had to report items from one RSVP series. Participants had to acknowledge and point out a certain letter and report other items that came after that letter. Results showed participants were more likely to report the items after the letter roughly around 400 milliseconds after the letter was presented. No spatial shift of attention was required. Participants only reported accurately the item following right after the cue but not any other item.

Broadbent and Broadbent (1987)^[5] discovered the attentional blink when they used a rapid serial visual presentation task to look at the recognition of multiple target words. Results showed that following the presence of a target, attentional processing is restricted and people can’t report the items that came after the target, however the presence of the item that comes after the target usually misses attentional blindness. This concludes that when two targets are shown within 500 milliseconds of one another and they are separated by one or more distractors, the second target usually falls within an attentional blink and will not be seen.

Inattentional blindness as also been looked at as a variation of the rapid serial visual presentation. Rees, Russell, Frith, and Driver (1999)^[6] investigated participants’ brain activity as they looked at rapid displays of a letter string or of a word above a picture. Participants were asked to watch out for repeats in the letter string or in the pictures that were displayed. They found that the attended words in the task were related to semantic processing.

Attentional blink

Modes of Rapid Serial Visual Presentation

There are two common modes that are used to describe rapid serial visual presentation.^[7] One of the modes is the static mode. Here, the pictures come into view and then disappear without moving. The other mode, the moving mode is where pictures come into view serially, move about the display and then disappear.

Static mode

The pictures in the rapid serial visual presentation have the same entry and exit locations. Pictures are shown one by one at the same rate. Here, participants must attend to a target that is shown for about 100 milliseconds. This is an advantage of this static mode. A disadvantage of the static mode is that there is no chance after that time to validate what was seen. The attentional blink which usually lasts between 300-400 milliseconds leads up to the other stimuli not being seen. The static mode can produce three different aspects when looking at an image: steady gaze, search to steady and visual search.

Moving modes

We are usually represented with presentations that rely a great deal on movement of pictures in a 2D plane. These are more difficult to register in comparison than pictures that move back and forth. The basic psychology of human visual perception explains that people are inclined to register imagery in a 3D world. This mode believes rapid serial visual presentation is important when approaching and processing objects. The moving mode can produce three different aspects when looking at an image: diagonal, stream and ring.

Advantages of RSVP over conventional reading

The unique method used by RSVP allows for the reading of unlimited text in a limited position. Researchers from Carnegie Mellon have found that as many as 12 words per second are readable in controlled situations (720wpm).^[8] Further research has shown that for shorter pieces of text, RSVP formats increased reading speed by 33% with no significant differences in comprehension or task load.^[9]

Research done by the Wichita State University suggests that at 250 words per minute (WPM) comprehension was not significantly different from reading done using Palm Reader (EReader). Display at 650 WPM reduced comprehension by about 20% versus display at 250 WPM, from a score of 74.6 to 52.1, resulting in an effective 82% increase in words comprehended per minute, assuming the scoring is linear.^[10] Studies have shown that reading rate is determined by size of text and spacing. RSVP allows users to obtain a maximum reading rate through the ability to adjust text size and eliminate space by displaying one item at a time.^[11]

Disadvantages and limitations

Several limitations are presented in the rapid serial visual presentation. The RSVP can cause an unnecessary need for cognitive demand. The memory load for each individual differs and can be high, because using RSVP, more attention is needed. Also, RSVP allows us to miss vital information.^[12] RSVP also often results with repetition blindness during use. When presented with a sequence of visual stimuli in rapid succession at the same location, readers often fail to detect words prominently repeated in a series, thus potentially missing the main ideas of the text. Other disadvantages include attentional blink, in which the mind focuses longer on certain words which may strike an emotional chord and puts the reader behind in a sequence, as well as temporal masking, causing certain words when being read aloud in a series may evoke a striking sound or response that makes inaudible the mental articulation of the following word.

Web browsing on small-screen devices

Using RSVP-based browsers offers a space–time trade-offs for information presentation on small screen devices such as cell phones and PDAs. However to make this solution functional location and context related questions like ‘Where am I’, ‘Where can I usefully go’, ‘Where have I been’ and ‘How do I get back to X’, need to be addressed.^[13]

Other uses

RSVP can aid those with poor eyesight with its one text at a time display that enlarges and highlights the words.

RSVP and peripheral reading

Peripheral reading is vital to those suffering from central field loss, which is most commonly seen in the elderly. Factors which might limit one's peripheral reading rate include acuity, crowding, and eye movements. Many find difficulty making the correct eye movements for peripheral reading, but the dependence on eye movements can be minimized through the presentation format of RSVP.^[14]

RSVP and adolescent sexual offenders

Limited existing previous research by Beech et al. suggests that images presented in RSVP have the potential to elicit a response from adolescent sexual offenders by measuring the effects of attentional blink. A stronger attentional blink is expected among adolescent sexual offenders after viewing a series of child related images. However, this hypothesis has not held up to subsequent research and remains an area of continued debate.^[15]

See also

• Speed reading

References