By Lisa M. Nimmo and Stephan Lewandowsky
Introduction
- Temporal isolation effect: the time between presented items effects the recall of these items
- Problem: some people argue that the increase in the amount of time between presentation provides more time to rehearse (an event) the items and thus increases the recall performance based on event and not time
- One study tried to prove that it was a time-base effect by randomizing the amount of time provided between presentations. There was no evidence of this.
- Visual versus auditory presentation also discussed. It was thought that the temporal isolation effect might emerge if the lists were presented auditorily and at random time intervals. However, this theory has been proven and disproved by a number of studies.
- Nimmo and Lewandowsky designed two experiments. They first tested the emergence of the temporal isolation effect from auditory presentation at random intervals. The second tested the benefits of auditory presentation over visual presentation at random intervals.
Experiment 1
- There were 36 participants from the University of Western Australia. They were randomly assigned to each condition.
- There were 2 conditions for this experiment: long intervals (450 – 4,400 msec) and short intervals (450 – 1600 msec). (n = 18 for both groups)
- They were presented lists with 7 items (7 of 19 letters) auditorily. All participants heard a female voice speaking English with an Australian accent at the same volume.
- Procedure:
- Tested in groups of 3
- 4 practice trials
- A break every 30 trials
- Lists presented with variation in the length of time between each item presented
- Took 60 to 75 minutes.
- Participants were encourages accuracy and latency.
- 120 trials
- List presented – recall – cleared – list presented – cycle continues
- Results:
- There was a serial position effect.
- Condition didn’t effect the serial position.
- Figure implies that there is no beneficial effect of either time interval.
- Statistical analysis supports these implications. No significant evidence that temporal isolation effects performance.
Experiment 2
- There were 20 participants from the University of Western Australia.
- There were two conditions: auditory (n= 11) and visual (n=9). The participants were randomly assigned.
- Received the same stimuli as in Experiment 1, however the interval was changed to 125 – 4000 msec and the 720 permutations were split into 2 sets of 360 trials.
- Procedure:
- The participants were presented either the auditory or visual condition.
- They did 90 trials per session.
- Each list took 12,875 msec to present and each letter was presented for 400 msec.
- The experiment took 4 hours
- List presented – recall – cleared – list presented – cycle continues
- Results:
- Again the serial position effect was present. Effect greater for auditory presentation.
- Found no consistent effect on recall performance for either auditory or visual presentation.
General Discussion
- Findings consistent with other findings – no evidence of the benefits of temporal isolation.
- Concluded:
- Temporal isolation has no effect on recall for auditory presentation even over wide range of intervals
- Auditory and visual presentation both show recall results insensitive to temporal isolation
- Problem – Did not account for rehearsal
- Some believe rehearsal actually enhances temporal isolation effect; supported because temporal isolation effect occurs when no rehearsal suppression but disappears with rehearsal suppression
- Thought that participants use interval pattern as a memory aid; if not pattern in present memory aid is gone
- Studies seem to show that it is not necessarily the length of time but what the length of time allows.
- If this is the case, there may be an event-based approach to memory.
- More research needs to be preformed.
Presentation by Sharon Triner