Model Answer
0 min readIntroduction
Sensory memory is the briefest form of memory, holding sensory information for a very short period after the original stimulus has ceased. It acts as a buffer, allowing us to process information before it’s transferred to short-term memory. George Sperling (1960) and Ulric Neisser (1967) conducted groundbreaking experiments to investigate the characteristics of this initial stage of memory. While both explored sensory memory, they employed different methodologies and focused on different aspects of its function, ultimately contributing significantly to our understanding of how information is initially registered and retained.
Sperling’s Experiment: Iconic Memory
Sperling’s experiment aimed to determine the capacity and duration of iconic memory – the visual sensory memory. Participants were briefly presented with a grid of letters (3x3) for 50 milliseconds. Immediately after, they were asked to recall as many letters as they could. Results showed participants could typically recall only 4-5 letters. To assess if the limited recall was due to a rapid decay of the image or a limitation in reporting, Sperling introduced a partial report technique. Participants were cued with a tone (high, medium, or low) to recall only letters from a specific row. This significantly improved recall to around 3-4 letters per row, suggesting that all nine letters were initially available in iconic memory but decayed rapidly.
Neisser’s Experiment: Pre-attentive Processing & Sensory Memory
Neisser’s experiments, detailed in his book “Cognitive Psychology” (1967), investigated the role of attention in sensory memory. He presented participants with two streams of digits – one auditory and one visual – simultaneously. Participants were asked to attend to only one stream (either auditory or visual) and recall the digits from that stream. Neisser found that participants could recall digits from the attended stream with reasonable accuracy, but also reported some recall of digits from the unattended stream. This demonstrated that information in the unattended stream was still being processed at a sensory level – a phenomenon he termed pre-attentive processing. He further explored this with tachistoscopic presentations of letters, finding that while participants could report some information from the briefly presented stimuli, the amount of information recalled was limited and heavily influenced by attentional focus.
Comparative Analysis
| Feature | Sperling’s Experiment | Neisser’s Experiment |
|---|---|---|
| Stimulus Modality | Visual (letters) | Auditory & Visual (digits, letters) |
| Primary Focus | Capacity & Duration of Iconic Memory | Role of Attention in Sensory Processing & Pre-attentive Processing |
| Methodology | Brief presentation followed by whole report & partial report | Dual-task paradigm (attending to one stream while monitoring another) & Tachistoscopic presentation |
| Key Finding | Iconic memory has a large capacity but very short duration (~0.5 seconds) | Information is processed at a sensory level even without attention (pre-attentive processing) |
What did these experiments prove?
- Sperling’s experiment conclusively demonstrated that iconic memory has a large capacity (around 9 items) but a very short duration (approximately 0.5 seconds). The rapid decay of the iconic image explains why we can only recall a limited amount of visual information without active rehearsal.
- Neisser’s experiment proved that sensory information is processed even when attention is directed elsewhere. This highlighted the existence of pre-attentive processing, where basic features of stimuli (like pitch or color) are registered even without conscious awareness. This laid the groundwork for understanding selective attention and the filtering of information.
Conclusion
Both Sperling and Neisser’s experiments were pivotal in establishing the existence and characteristics of sensory memory. Sperling quantified its capacity and duration, while Neisser revealed the role of attention and pre-attentive processing. Their work collectively demonstrated that sensory memory isn’t a passive storage system but an active process involving initial analysis of incoming information, setting the stage for further cognitive processing. Future research continues to refine our understanding of the complexities of sensory memory and its interaction with attention and other cognitive systems.
Answer Length
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