Sensory Memory Systems. Visual Store. PDF created with pdffactory trial version

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1 Sensory Memory Systems Visual Store Jevons (1871) estimate the number of beans. Accurate estimations up to 9 beans (span of apprehension). Averbach(1963) Tachistoscopic display Estimate how many dots are presented How many of you got it right? Now try again, how many are dots are being presented now? How many of you got it right? 1

2 Averbach s results: Accuracy improves with presentation duration and declines with the number of dots in the display Sperling (1960) Compared performance in two tasks: Full report and partial report. The partial report task was used to bypass the report bottleneck Full report: Write down as many items as you can 6 V I A L 4 K D 1 3 M U Write down what you remember This is what was presented. How many letters did you remember correctly? 6 V I A L 4 K D 1 3 M U 2

3 Partial report: Write down as many items as you can from the marked line (the line was marked by a tone in the original experiment) F 3 E 2 W L T R S 5 Z C Estimated amount of information available when the line was marked: Proportion of correctly reported items from the given line times the number items in the entire display What you saw on the relevant line was E R 5 C Compute the estimate for how many items you remembered from the entire display. It this score better than your full report score? Sperling manipulated the interval between the display and the tone The advantage of partial report over full report is eliminated by about.5 sec, showing evidence for 2 things: Report bottleneck Availability of most of the information in a relatively raw (pre-reportable) format for a brief duration Explaining the effect 3 F 4 G S M 5 P R 7 K L 3

4 Iconic memory (Neisser s term) or visual information store (Sperling s term) reflects Information persistence. Stimulus persistence is measured by flickering a stimulus and determining the maximal length of the empty intervals which do not disrupt the continuous percept. This duration is ms (Haber and Standing, 1969). Iconic memory is not an afterimage (Banks & Barber, 1977) because subjects do not report the complementary colors (red for green, yellow for blue). The icon is erased by pattern masks F 3 E 2 T R W S 5 L Z C Even when these masks are presented to the other eye (Turvey, 1973) (which is not true for brightness masks, which work on level of the eye) Partial report >Full report may be partially due to output interference. This advantage is absent for the first reported item (for which there is no output interference, Dick, 1971) IM is different from stimulus persistence because stimulus persistence is affected by stimulus presentation duration whereas IM is unaffected by how long the matrix is presented (Yeomans & Irwin, 1985). 4

5 Experiment1 100 ms 900 ms 2,000 ms different same Results: Load: verbal load of 2 digits 5

6 Experiment 2 Can the results be explained by other factors than WM maintenance, such as encoding or decision factors: Encoding sample stimulus duration was manipulated to be 100 ms or 500 ms. Decision factors the target array indicated a square (cue) around one item only, and the subjects had to decide whether this item was changed. Experiment 3 Is visual WM capacity similar for different visual dimensions? Is information stored in WM as features or as integrated objects? Experiment 4 Extension of the results of Experiment 3, using 4 dimensions color, orientation, size and gap. (namely, 4 items are composed of 16 features) 6

7 Experiment 5 A limitation on the number of integrated objects rather than on the number of features can stem from different memory systems for different types of features. Experiment 5 examined conjunctions of 2 features of the same type (color). Experiment 1 Goal: replication of Luck & Vogel (1997) 7

8 Experiment 1 Results: Experiment 2 Another attempt to replicate Luck & Vogel Experiment 3a Investigation of memory for bindings (not examined by L & V) 8

9 Results: Experiment 3b Similar to Experiment 3a, but used single-probe test Features and feature bindings are held in separate stores (which is why they are differentially sensitive to testing mode: Only bindings show a decrement when tested in the whole display probe.) The possible reason is that attention is required to keep the bindings together. When the probe requires considering the combination, attention is diverted, which results in a storage impairment. 9

10 It takes 50 ms to store a single item in visual WM (Vogel et al., 2005) 50 ms Echoic memory Darwin et al., 1972, presented 3 digit triads simultaneously, and made it feel as if the triads came from three different locations (by playing with the relative sound level reaching the two ears), and cued visually which triad to report There is a partial report advantage similar to that as found in vision 10

11 PAS (Precategorical Acustic Store,(Crowder & Morton, 1968): Information is present in a precategorical form for ~ 2 sec Robert G. Crowder Serial recall presented items and used a free recall procedure (recall the items in any order). The recency effect is found for auditory presentation but not for visual presentation. Recency effects are diminished when the auditory information is made less useful (homophones such as write, right, and rite, Crowder, 1978) Suffix effect: Old information in PAS is overwritten by new information. Problems with PAS: It is assuming that information is auditory, but not speech related, but the evidence shows it to be speech related The recency effect is diminished by adding a suffix after presenting the last item if the suffix is speech ( zero ) And not when it is nonspeech (buzzer sound) 11

12 The recency effect is speech specific because if the suffix, the spoken syllable wa is described as speech, it reduces the recency effect but not when it is described as coming from a plunger muted trumpet (Ayres, et al., 1979) Similarly, non-speech sounds (dog and cow sounds) are described as speech, they reduce the recency effect (Neath et al., 1993) 12

13 Results: Load: verbal load of 2 digits

14 Experiment 2 Can the results be explained by other factors than WM maintenance, such as encoding or decision factors: Encoding sample stimulus duration was manipulated to be 100 ms or 500 ms. Decision factors the target array indicated a square (cue) around one item only, and the subjects had to decide whether this item was changed.

15 Experiment 3 Is visual WM capacity similar for different visual dimensions? Is information stored in WM as features or as integrated objects?

16 Experiment 4 Extension of the results of Experiment 3, using 4 dimensions color, orientation, size and gap. (namely, 4 items are composed of 16 features)

17 Experiment 5 A limitation on the number of integrated objects rather than on the number of features can stem from different memory systems for different types of features. Experiment 5 examined conjunctions of 2 features of the same type (color).

18 Experiment 1 Results:

19 Experiment 2 Another attempt to replicate Luck & Vogel

20 Results:

21 Experiment 3b Similar to Experiment 3a, but used single-probe test

22 It takes 50 ms to store a single item in visual WM (Vogel et al., 2005) 50 ms

23 There is a partial report advantage similar to that as found in vision

24 PAS (Precategorical Acustic Store,(Crowder & Morton, 1968): Information is present in a precategorical form for ~ 2 sec Robert G. Crowder Serial recall presented items and used a free recall procedure (recall the items in any order). The recency effect is found for auditory presentation but not for visual presentation. Recency effects are diminished when the auditory information is made less useful (homophones such as write, right, and rite, Crowder, 1978)

25 Problems with PAS: It is assuming that information is auditory, but not speech related, but the evidence shows it to be speech related The recency effect is diminished by adding a suffix after presenting the last item if the suffix is speech ( zero ) And not when it is nonspeech (buzzer sound)

26 The recency effect is speech specific because if the suffix, the spoken syllable wa is described as speech, it reduces the recency effect but not when it is described as coming from a plunger muted trumpet (Ayres, et al., 1979) Similarly, non-speech sounds (dog and cow sounds) are described as speech, they reduce the recency effect (Neath et al., 1993)