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- Angelo Santi, Dwayne Keough, and Patrick Van Rooyen
- Wilfrid Laurier University
- Waterloo, Ontario, Canada
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- Mantanus (1981) - filled intervals discriminated more accurately than
empty intervals.
- Kraemer, Randall, and Brown (1997) - filled interval (houselight on)
judged to be longer than an empty interval (houselight off) of
equivalent physical duration.
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4
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5
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6
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7
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- PSE difference between empty and filled intervals increased as the
anchor duration values increased
- Suggests that for pigeons the accumulation of subjective time may be
greater for empty intervals than for filled intervals
- Limitation of the study
- same stimulus was used to signal filled intervals and to mark empty
intervals.
- timing from the onset of the first marker to the offset of the sec=
ond
marker would result in the empty intervals being 1 s longer than
filled intervals
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- 1) Demonstrate that empty intervals are judged to be longer than fil=
led
intervals even when different stimuli are used to signal filled
intervals and to mark empty intervals.
- 2) Demonstrate that this timing difference is not the result of pige=
ons
timing the markers on empty interval trials.
- 3) Test an attentional explanation of this difference
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- 160 trials per session
- 80 (40E,40F) – 2 and 8 s anchor durations – with correct
responses reinforced
- 80 (40E,40F) – one of 5 intermediate durations – no
reinforcement
- 20 sessions of testing
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- 160 empty interval trials per test session
- 80 trials – 1s markers
- 40anchor / 40intermediate
- 40 trials – 0.5s markers
- 20anchor / 20intermediate
- 40 trials – 2.0s markers
- 20anchor / 20intermediate
- 20 test sessions in total
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- PSE: E0.5 =3D 3.58 E1 =
=3D
3.51 E2 =3D 3.42 n.s.<=
/li>
- DL: E0.5 =3D 0.95 E1 =3D 0.89 E2 =3D 0.87 n.s.
- WF: E0.5 =3D 0.26 E1 =
=3D
0.25 E2 =3D 0.25 n.s.<=
/li>
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15
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- Attentional Explanation:
- reduction in attention to processing temporal properties during fil=
led
intervals
- filled intervals of light might allow for visual features in the
chamber to attract attention, thereby reducing attention to process=
ing
the temporal properties of the signal
- empty intervals spent in darkness may result in more attention to timing w=
ith no
competition from nontemporal (visual) features
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- Assess percepti=
on of
empty and filled intervals with background conditions dark or
illuminated
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19
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20
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- Required pecking alters time judgments
- Underestimation of time intervals when pigeons are active –
attention to time related cues shared with meeting response requirem=
ents
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- Pigeons judge empty intervals to be longer than equal-length filled
intervals
- even when different stimuli are used to mark empty intervals and to
signal filled intervals.
- The timing difference is not a result of timing marker duration on e=
mpty
interval trials
- increasing marker duration did not produce an overestimation of the
empty time intervals
- The timing difference may be a result of a reduction in attention to
temporal processing on filled interval trials when visual signals are
used
- Empty intervals are judged longer than filled intervals when testing
occurs in a darkened test room, but not when the test room is
illuminated
- No PSE difference with auditory signals and cues
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