SPEED OF INFORMATION PROCESSING - AS A MEASURE OF INTELLIGENCE
Studies of reaction time and inspection time In the 1970s Arthur Jensen began a research programme investigating the possibility that intelligence, or psychometric g, is based on the speed with which we process information. Jensen thought that the latter might be measured without asking any of the conventional questions found in intelligence tests, thereby avoiding concerns about cultural bias (more about that later). To measure speed of processing, Jensen used a very simple reaction time (RT) procedure, (reaction time (RT) the time taken to process a single bit of information: the stimulus is seen until a decision is made and response is completed) in which participants have to respond quickly to the onset of a light. He found that individuals with higher IQs respond faster and are more consistent in the speed of their responses. Jensen (1982) claimed that the basis of individual differences in intelligence is to be found in the speed with which we process a single bit of information (as evaluated, for example, by his speed of information processing task). (speed of information processing the speed with which an individual can take in information from their environment; the speed of perceptual encoding.) Jensen proposed that this capacity may be underpinned by the rate of oscillation of excitatory and inhibitory phases of neuronal firing. While these findings were exciting, reaction time experiments were subsequently criticized on the basis that the response time could be confounded by the speed or organization of motor responses and task strategies, rather than being a pure measure of speed of intellectual processing. In the 1970s an Australian researcher, Doug Vickers, addressed this concern by developing the inspection time (IT) task (inspection time (IT) the time taken to process a single bit of information: the stimulus is seen (inspected) for a very short time before disappearing) in which it does not matter how long participants take to respond to a presented stimulus, so motor organization is no longer an issue. Instead, the length of time they are exposed to the stimulus is controlled by varying the time of stimulus presentation before the onset of a following masking stimulus (this is a figure that effectively destroys the information from the target stimulus). Interestingly, the decision task itself does not get any more complex – it is only the decreasing exposure duration that makes the task increasingly difficult.
[Arthur Jensen (1923– ) articulated an influential body of thought regarding IQ and processing speed. In the 1970s, Jensen began a research programme investigating the possibility that intelligence, or psychometric g, is based on the speed with which we process information. To measure speed of processing, Jensen and his colleagues used a very simple reaction time task. They found that individuals with higher IQs responded faster and were more consistent in the speed of their responses. The application of the reaction time technique to the study of IQ has since been criticized, but it has stimulated a considerable volume of work in related areas, such as in the use of inspection time as a complementary methodology. Jensen has also written controversially on the topic of IQ and race.]
The IT task was made simple enough for children with intellectual disabilities to discriminate between two line lengths after seeing the stimulus for only 200 –300 ms. Participants with higher IQs can make the discrimination at shorter exposure durations – that is, they have shorter inspection times of around 100 ms. Child-friendly versions of the inspection time task use ‘spaceinvader’ type computer games, where the discrimination relates to the relative height of an alien’s antennae (Anderson, 1988; Scheuffgen et al., 2000). In careful reviews of many studies, Nettelbeck (1987) and Kranzler and Jensen (1989) came to the conclusion that inspection time and IQ correlate negatively at about −0.5. In other words, the speed of processing a ‘simple’ unit of information predicts about 25 per cent of the individual differences we find in intellectual performance, as measured by a typical intelligence test. (Note, the square of a correlation, r2, indicates the shared variance between two variables.) Inspection time continues to be of great interest in helping us understand the nature of intelligence (Burns & Nettelbeck, 2003).
Studies of reaction time and inspection time In the 1970s Arthur Jensen began a research programme investigating the possibility that intelligence, or psychometric g, is based on the speed with which we process information. Jensen thought that the latter might be measured without asking any of the conventional questions found in intelligence tests, thereby avoiding concerns about cultural bias (more about that later). To measure speed of processing, Jensen used a very simple reaction time (RT) procedure, (reaction time (RT) the time taken to process a single bit of information: the stimulus is seen until a decision is made and response is completed) in which participants have to respond quickly to the onset of a light. He found that individuals with higher IQs respond faster and are more consistent in the speed of their responses. Jensen (1982) claimed that the basis of individual differences in intelligence is to be found in the speed with which we process a single bit of information (as evaluated, for example, by his speed of information processing task). (speed of information processing the speed with which an individual can take in information from their environment; the speed of perceptual encoding.) Jensen proposed that this capacity may be underpinned by the rate of oscillation of excitatory and inhibitory phases of neuronal firing. While these findings were exciting, reaction time experiments were subsequently criticized on the basis that the response time could be confounded by the speed or organization of motor responses and task strategies, rather than being a pure measure of speed of intellectual processing. In the 1970s an Australian researcher, Doug Vickers, addressed this concern by developing the inspection time (IT) task (inspection time (IT) the time taken to process a single bit of information: the stimulus is seen (inspected) for a very short time before disappearing) in which it does not matter how long participants take to respond to a presented stimulus, so motor organization is no longer an issue. Instead, the length of time they are exposed to the stimulus is controlled by varying the time of stimulus presentation before the onset of a following masking stimulus (this is a figure that effectively destroys the information from the target stimulus). Interestingly, the decision task itself does not get any more complex – it is only the decreasing exposure duration that makes the task increasingly difficult.
[Arthur Jensen (1923– ) articulated an influential body of thought regarding IQ and processing speed. In the 1970s, Jensen began a research programme investigating the possibility that intelligence, or psychometric g, is based on the speed with which we process information. To measure speed of processing, Jensen and his colleagues used a very simple reaction time task. They found that individuals with higher IQs responded faster and were more consistent in the speed of their responses. The application of the reaction time technique to the study of IQ has since been criticized, but it has stimulated a considerable volume of work in related areas, such as in the use of inspection time as a complementary methodology. Jensen has also written controversially on the topic of IQ and race.]
The IT task was made simple enough for children with intellectual disabilities to discriminate between two line lengths after seeing the stimulus for only 200 –300 ms. Participants with higher IQs can make the discrimination at shorter exposure durations – that is, they have shorter inspection times of around 100 ms. Child-friendly versions of the inspection time task use ‘spaceinvader’ type computer games, where the discrimination relates to the relative height of an alien’s antennae (Anderson, 1988; Scheuffgen et al., 2000). In careful reviews of many studies, Nettelbeck (1987) and Kranzler and Jensen (1989) came to the conclusion that inspection time and IQ correlate negatively at about −0.5. In other words, the speed of processing a ‘simple’ unit of information predicts about 25 per cent of the individual differences we find in intellectual performance, as measured by a typical intelligence test. (Note, the square of a correlation, r2, indicates the shared variance between two variables.) Inspection time continues to be of great interest in helping us understand the nature of intelligence (Burns & Nettelbeck, 2003).
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